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android / platform / libcore / 71f2c75111e87091616f0f3b86bea6c4d345dad1 / . / src / hotspot / os / posix / os_posix.cpp
blob: c0a0c96222bcfdbb439b748f7b8902f5327d563c [file] [log] [blame]
/*
* Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "jvm.h"
#include "logging/log.hpp"
#include "memory/allocation.inline.hpp"
#include "utilities/globalDefinitions.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/interfaceSupport.inline.hpp"
#include "runtime/os.hpp"
#include "services/memTracker.hpp"
#include "utilities/align.hpp"
#include "utilities/events.hpp"
#include "utilities/formatBuffer.hpp"
#include "utilities/macros.hpp"
#include "utilities/vmError.hpp"
#include <dlfcn.h>
#include <grp.h>
#include <pwd.h>
#include <pthread.h>
#include <signal.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <sys/utsname.h>
#include <time.h>
#include <unistd.h>
#include <utmpx.h>
// Todo: provide a os::get_max_process_id() or similar. Number of processes
// may have been configured, can be read more accurately from proc fs etc.
#ifndef MAX_PID
#define MAX_PID INT_MAX
#endif
#define IS_VALID_PID(p) (p > 0 && p < MAX_PID)
#define ROOT_UID 0
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
#define check_with_errno(check_type, cond, msg) \
do { \
int err = errno; \
check_type(cond, "%s; error='%s' (errno=%s)", msg, os::strerror(err), \
os::errno_name(err)); \
} while (false)
#define assert_with_errno(cond, msg) check_with_errno(assert, cond, msg)
#define guarantee_with_errno(cond, msg) check_with_errno(guarantee, cond, msg)
// Check core dump limit and report possible place where core can be found
void os::check_dump_limit(char* buffer, size_t bufferSize) {
if (!FLAG_IS_DEFAULT(CreateCoredumpOnCrash) && !CreateCoredumpOnCrash) {
jio_snprintf(buffer, bufferSize, "CreateCoredumpOnCrash is disabled from command line");
VMError::record_coredump_status(buffer, false);
return;
}
int n;
struct rlimit rlim;
bool success;
char core_path[PATH_MAX];
n = get_core_path(core_path, PATH_MAX);
if (n <= 0) {
jio_snprintf(buffer, bufferSize, "core.%d (may not exist)", current_process_id());
success = true;
#ifdef LINUX
} else if (core_path[0] == '"') { // redirect to user process
jio_snprintf(buffer, bufferSize, "Core dumps may be processed with %s", core_path);
success = true;
#endif
} else if (getrlimit(RLIMIT_CORE, &rlim) != 0) {
jio_snprintf(buffer, bufferSize, "%s (may not exist)", core_path);
success = true;
} else {
switch(rlim.rlim_cur) {
case RLIM_INFINITY:
jio_snprintf(buffer, bufferSize, "%s", core_path);
success = true;
break;
case 0:
jio_snprintf(buffer, bufferSize, "Core dumps have been disabled. To enable core dumping, try \"ulimit -c unlimited\" before starting Java again");
success = false;
break;
default:
jio_snprintf(buffer, bufferSize, "%s (max size " UINT64_FORMAT " kB). To ensure a full core dump, try \"ulimit -c unlimited\" before starting Java again", core_path, uint64_t(rlim.rlim_cur) / 1024);
success = true;
break;
}
}
VMError::record_coredump_status(buffer, success);
}
int os::get_native_stack(address* stack, int frames, int toSkip) {
int frame_idx = 0;
int num_of_frames; // number of frames captured
frame fr = os::current_frame();
while (fr.pc() && frame_idx < frames) {
if (toSkip > 0) {
toSkip --;
} else {
stack[frame_idx ++] = fr.pc();
}
if (fr.fp() == NULL || fr.cb() != NULL ||
fr.sender_pc() == NULL || os::is_first_C_frame(&fr)) break;
if (fr.sender_pc() && !os::is_first_C_frame(&fr)) {
fr = os::get_sender_for_C_frame(&fr);
} else {
break;
}
}
num_of_frames = frame_idx;
for (; frame_idx < frames; frame_idx ++) {
stack[frame_idx] = NULL;
}
return num_of_frames;
}
bool os::unsetenv(const char* name) {
assert(name != NULL, "Null pointer");
return (::unsetenv(name) == 0);
}
int os::get_last_error() {
return errno;
}
bool os::is_debugger_attached() {
// not implemented
return false;
}
void os::wait_for_keypress_at_exit(void) {
// don't do anything on posix platforms
return;
}
int os::create_file_for_heap(const char* dir) {
const char name_template[] = "/jvmheap.XXXXXX";
size_t fullname_len = strlen(dir) + strlen(name_template);
char *fullname = (char*)os::malloc(fullname_len + 1, mtInternal);
if (fullname == NULL) {
vm_exit_during_initialization(err_msg("Malloc failed during creation of backing file for heap (%s)", os::strerror(errno)));
return -1;
}
int n = snprintf(fullname, fullname_len + 1, "%s%s", dir, name_template);
assert((size_t)n == fullname_len, "Unexpected number of characters in string");
os::native_path(fullname);
sigset_t set, oldset;
int ret = sigfillset(&set);
assert_with_errno(ret == 0, "sigfillset returned error");
// set the file creation mask.
mode_t file_mode = S_IRUSR | S_IWUSR;
// create a new file.
int fd = mkstemp(fullname);
if (fd < 0) {
warning("Could not create file for heap with template %s", fullname);
os::free(fullname);
return -1;
}
// delete the name from the filesystem. When 'fd' is closed, the file (and space) will be deleted.
ret = unlink(fullname);
assert_with_errno(ret == 0, "unlink returned error");
os::free(fullname);
return fd;
}
static char* reserve_mmapped_memory(size_t bytes, char* requested_addr) {
char * addr;
int flags = MAP_PRIVATE NOT_AIX( | MAP_NORESERVE ) | MAP_ANONYMOUS;
if (requested_addr != NULL) {
assert((uintptr_t)requested_addr % os::vm_page_size() == 0, "Requested address should be aligned to OS page size");
flags |= MAP_FIXED;
}
// Map reserved/uncommitted pages PROT_NONE so we fail early if we
// touch an uncommitted page. Otherwise, the read/write might
// succeed if we have enough swap space to back the physical page.
addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
flags, -1, 0);
if (addr != MAP_FAILED) {
MemTracker::record_virtual_memory_reserve((address)addr, bytes, CALLER_PC);
return addr;
}
return NULL;
}
static int util_posix_fallocate(int fd, off_t offset, off_t len) {
#ifdef __APPLE__
fstore_t store = { F_ALLOCATECONTIG, F_PEOFPOSMODE, 0, len };
// First we try to get a continuous chunk of disk space
int ret = fcntl(fd, F_PREALLOCATE, &store);
if (ret == -1) {
// Maybe we are too fragmented, try to allocate non-continuous range
store.fst_flags = F_ALLOCATEALL;
ret = fcntl(fd, F_PREALLOCATE, &store);
}
if(ret != -1) {
return ftruncate(fd, len);
}
return -1;
#else
return posix_fallocate(fd, offset, len);
#endif
}
// Map the given address range to the provided file descriptor.
char* os::map_memory_to_file(char* base, size_t size, int fd) {
assert(fd != -1, "File descriptor is not valid");
// allocate space for the file
int ret = util_posix_fallocate(fd, 0, (off_t)size);
if (ret != 0) {
vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory. error(%d)", ret));
return NULL;
}
int prot = PROT_READ | PROT_WRITE;
int flags = MAP_SHARED;
if (base != NULL) {
flags |= MAP_FIXED;
}
char* addr = (char*)mmap(base, size, prot, flags, fd, 0);
if (addr == MAP_FAILED) {
warning("Failed mmap to file. (%s)", os::strerror(errno));
return NULL;
}
if (base != NULL && addr != base) {
if (!os::release_memory(addr, size)) {
warning("Could not release memory on unsuccessful file mapping");
}
return NULL;
}
return addr;
}
char* os::replace_existing_mapping_with_file_mapping(char* base, size_t size, int fd) {
assert(fd != -1, "File descriptor is not valid");
assert(base != NULL, "Base cannot be NULL");
return map_memory_to_file(base, size, fd);
}
// Multiple threads can race in this code, and can remap over each other with MAP_FIXED,
// so on posix, unmap the section at the start and at the end of the chunk that we mapped
// rather than unmapping and remapping the whole chunk to get requested alignment.
char* os::reserve_memory_aligned(size_t size, size_t alignment, int file_desc) {
assert((alignment & (os::vm_allocation_granularity() - 1)) == 0,
"Alignment must be a multiple of allocation granularity (page size)");
assert((size & (alignment -1)) == 0, "size must be 'alignment' aligned");
size_t extra_size = size + alignment;
assert(extra_size >= size, "overflow, size is too large to allow alignment");
char* extra_base;
if (file_desc != -1) {
// For file mapping, we do not call os:reserve_memory(extra_size, NULL, alignment, file_desc) because
// we need to deal with shrinking of the file space later when we release extra memory after alignment.
// We also cannot called os:reserve_memory() with file_desc set to -1 because on aix we might get SHM memory.
// So here to call a helper function while reserve memory for us. After we have a aligned base,
// we will replace anonymous mapping with file mapping.
extra_base = reserve_mmapped_memory(extra_size, NULL);
if (extra_base != NULL) {
MemTracker::record_virtual_memory_reserve((address)extra_base, extra_size, CALLER_PC);
}
} else {
extra_base = os::reserve_memory(extra_size, NULL, alignment);
}
if (extra_base == NULL) {
return NULL;
}
// Do manual alignment
char* aligned_base = align_up(extra_base, alignment);
// [ | | ]
// ^ extra_base
// ^ extra_base + begin_offset == aligned_base
// extra_base + begin_offset + size ^
// extra_base + extra_size ^
// |<>| == begin_offset
// end_offset == |<>|
size_t begin_offset = aligned_base - extra_base;
size_t end_offset = (extra_base + extra_size) - (aligned_base + size);
if (begin_offset > 0) {
os::release_memory(extra_base, begin_offset);
}
if (end_offset > 0) {
os::release_memory(extra_base + begin_offset + size, end_offset);
}
if (file_desc != -1) {
// After we have an aligned address, we can replace anonymous mapping with file mapping
if (replace_existing_mapping_with_file_mapping(aligned_base, size, file_desc) == NULL) {
vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory"));
}
MemTracker::record_virtual_memory_commit((address)aligned_base, size, CALLER_PC);
}
return aligned_base;
}
int os::vsnprintf(char* buf, size_t len, const char* fmt, va_list args) {
// All supported POSIX platforms provide C99 semantics.
int result = ::vsnprintf(buf, len, fmt, args);
// If an encoding error occurred (result < 0) then it's not clear
// whether the buffer is NUL terminated, so ensure it is.
if ((result < 0) && (len > 0)) {
buf[len - 1] = '\0';
}
return result;
}
int os::get_fileno(FILE* fp) {
return NOT_AIX(::)fileno(fp);
}
struct tm* os::gmtime_pd(const time_t* clock, struct tm* res) {
return gmtime_r(clock, res);
}
void os::Posix::print_load_average(outputStream* st) {
st->print("load average:");
double loadavg[3];
int res = os::loadavg(loadavg, 3);
if (res != -1) {
st->print("%0.02f %0.02f %0.02f", loadavg[0], loadavg[1], loadavg[2]);
} else {
st->print(" Unavailable");
}
st->cr();
}
// boot/uptime information;
// unfortunately it does not work on macOS and Linux because the utx chain has no entry
// for reboot at least on my test machines
void os::Posix::print_uptime_info(outputStream* st) {
int bootsec = -1;
int currsec = time(NULL);
struct utmpx* ent;
setutxent();
while ((ent = getutxent())) {
if (!strcmp("system boot", ent->ut_line)) {
bootsec = ent->ut_tv.tv_sec;
break;
}
}
if (bootsec != -1) {
os::print_dhm(st, "OS uptime:", (long) (currsec-bootsec));
}
}
static void print_rlimit(outputStream* st, const char* msg,
int resource, bool output_k = false) {
struct rlimit rlim;
st->print(" %s ", msg);
int res = getrlimit(resource, &rlim);
if (res == -1) {
st->print("could not obtain value");
} else {
// soft limit
if (rlim.rlim_cur == RLIM_INFINITY) { st->print("infinity"); }
else {
if (output_k) { st->print(UINT64_FORMAT "k", uint64_t(rlim.rlim_cur) / 1024); }
else { st->print(UINT64_FORMAT, uint64_t(rlim.rlim_cur)); }
}
// hard limit
st->print("/");
if (rlim.rlim_max == RLIM_INFINITY) { st->print("infinity"); }
else {
if (output_k) { st->print(UINT64_FORMAT "k", uint64_t(rlim.rlim_max) / 1024); }
else { st->print(UINT64_FORMAT, uint64_t(rlim.rlim_max)); }
}
}
}
void os::Posix::print_rlimit_info(outputStream* st) {
st->print("rlimit (soft/hard):");
print_rlimit(st, "STACK", RLIMIT_STACK, true);
print_rlimit(st, ", CORE", RLIMIT_CORE, true);
#if defined(AIX)
st->print(", NPROC ");
st->print("%d", sysconf(_SC_CHILD_MAX));
print_rlimit(st, ", THREADS", RLIMIT_THREADS);
#elif !defined(SOLARIS)
print_rlimit(st, ", NPROC", RLIMIT_NPROC);
#endif
print_rlimit(st, ", NOFILE", RLIMIT_NOFILE);
print_rlimit(st, ", AS", RLIMIT_AS, true);
print_rlimit(st, ", CPU", RLIMIT_CPU);
print_rlimit(st, ", DATA", RLIMIT_DATA, true);
// maximum size of files that the process may create
print_rlimit(st, ", FSIZE", RLIMIT_FSIZE, true);
#if defined(LINUX) || defined(__APPLE__)
// maximum number of bytes of memory that may be locked into RAM
// (rounded down to the nearest multiple of system pagesize)
print_rlimit(st, ", MEMLOCK", RLIMIT_MEMLOCK, true);
#endif
#if defined(SOLARIS)
// maximum size of mapped address space of a process in bytes;
// if the limit is exceeded, mmap and brk fail
print_rlimit(st, ", VMEM", RLIMIT_VMEM, true);
#endif
// MacOS; The maximum size (in bytes) to which a process's resident set size may grow.
#if defined(__APPLE__)
print_rlimit(st, ", RSS", RLIMIT_RSS, true);
#endif
st->cr();
}
void os::Posix::print_uname_info(outputStream* st) {
// kernel
st->print("uname:");
struct utsname name;
uname(&name);
st->print("%s ", name.sysname);
#ifdef ASSERT
st->print("%s ", name.nodename);
#endif
st->print("%s ", name.release);
st->print("%s ", name.version);
st->print("%s", name.machine);
st->cr();
}
void os::Posix::print_umask(outputStream* st, mode_t umsk) {
st->print((umsk & S_IRUSR) ? "r" : "-");
st->print((umsk & S_IWUSR) ? "w" : "-");
st->print((umsk & S_IXUSR) ? "x" : "-");
st->print((umsk & S_IRGRP) ? "r" : "-");
st->print((umsk & S_IWGRP) ? "w" : "-");
st->print((umsk & S_IXGRP) ? "x" : "-");
st->print((umsk & S_IROTH) ? "r" : "-");
st->print((umsk & S_IWOTH) ? "w" : "-");
st->print((umsk & S_IXOTH) ? "x" : "-");
}
void os::Posix::print_user_info(outputStream* st) {
unsigned id = (unsigned) ::getuid();
st->print("uid : %u ", id);
id = (unsigned) ::geteuid();
st->print("euid : %u ", id);
id = (unsigned) ::getgid();
st->print("gid : %u ", id);
id = (unsigned) ::getegid();
st->print_cr("egid : %u", id);
st->cr();
mode_t umsk = ::umask(0);
::umask(umsk);
st->print("umask: %04o (", (unsigned) umsk);
print_umask(st, umsk);
st->print_cr(")");
st->cr();
}
bool os::get_host_name(char* buf, size_t buflen) {
struct utsname name;
uname(&name);
jio_snprintf(buf, buflen, "%s", name.nodename);
return true;
}
bool os::has_allocatable_memory_limit(julong* limit) {
struct rlimit rlim;
int getrlimit_res = getrlimit(RLIMIT_AS, &rlim);
// if there was an error when calling getrlimit, assume that there is no limitation
// on virtual memory.
bool result;
if ((getrlimit_res != 0) || (rlim.rlim_cur == RLIM_INFINITY)) {
result = false;
} else {
*limit = (julong)rlim.rlim_cur;
result = true;
}
#ifdef _LP64
return result;
#else
// arbitrary virtual space limit for 32 bit Unices found by testing. If
// getrlimit above returned a limit, bound it with this limit. Otherwise
// directly use it.
const julong max_virtual_limit = (julong)3800*M;
if (result) {
*limit = MIN2(*limit, max_virtual_limit);
} else {
*limit = max_virtual_limit;
}
// bound by actually allocatable memory. The algorithm uses two bounds, an
// upper and a lower limit. The upper limit is the current highest amount of
// memory that could not be allocated, the lower limit is the current highest
// amount of memory that could be allocated.
// The algorithm iteratively refines the result by halving the difference
// between these limits, updating either the upper limit (if that value could
// not be allocated) or the lower limit (if the that value could be allocated)
// until the difference between these limits is "small".
// the minimum amount of memory we care about allocating.
const julong min_allocation_size = M;
julong upper_limit = *limit;
// first check a few trivial cases
if (is_allocatable(upper_limit) || (upper_limit <= min_allocation_size)) {
*limit = upper_limit;
} else if (!is_allocatable(min_allocation_size)) {
// we found that not even min_allocation_size is allocatable. Return it
// anyway. There is no point to search for a better value any more.
*limit = min_allocation_size;
} else {
// perform the binary search.
julong lower_limit = min_allocation_size;
while ((upper_limit - lower_limit) > min_allocation_size) {
julong temp_limit = ((upper_limit - lower_limit) / 2) + lower_limit;
temp_limit = align_down(temp_limit, min_allocation_size);
if (is_allocatable(temp_limit)) {
lower_limit = temp_limit;
} else {
upper_limit = temp_limit;
}
}
*limit = lower_limit;
}
return true;
#endif
}
const char* os::get_current_directory(char *buf, size_t buflen) {
return getcwd(buf, buflen);
}
FILE* os::open(int fd, const char* mode) {
return ::fdopen(fd, mode);
}
void os::flockfile(FILE* fp) {
::flockfile(fp);
}
void os::funlockfile(FILE* fp) {
::funlockfile(fp);
}
DIR* os::opendir(const char* dirname) {
assert(dirname != NULL, "just checking");
return ::opendir(dirname);
}
struct dirent* os::readdir(DIR* dirp) {
assert(dirp != NULL, "just checking");
return ::readdir(dirp);
}
int os::closedir(DIR *dirp) {
assert(dirp != NULL, "just checking");
return ::closedir(dirp);
}
// Builds a platform dependent Agent_OnLoad_<lib_name> function name
// which is used to find statically linked in agents.
// Parameters:
// sym_name: Symbol in library we are looking for
// lib_name: Name of library to look in, NULL for shared libs.
// is_absolute_path == true if lib_name is absolute path to agent
// such as "/a/b/libL.so"
// == false if only the base name of the library is passed in
// such as "L"
char* os::build_agent_function_name(const char *sym_name, const char *lib_name,
bool is_absolute_path) {
char *agent_entry_name;
size_t len;
size_t name_len;
size_t prefix_len = strlen(JNI_LIB_PREFIX);
size_t suffix_len = strlen(JNI_LIB_SUFFIX);
const char *start;
if (lib_name != NULL) {
name_len = strlen(lib_name);
if (is_absolute_path) {
// Need to strip path, prefix and suffix
if ((start = strrchr(lib_name, *os::file_separator())) != NULL) {
lib_name = ++start;
}
if (strlen(lib_name) <= (prefix_len + suffix_len)) {
return NULL;
}
lib_name += prefix_len;
name_len = strlen(lib_name) - suffix_len;
}
}
len = (lib_name != NULL ? name_len : 0) + strlen(sym_name) + 2;
agent_entry_name = NEW_C_HEAP_ARRAY_RETURN_NULL(char, len, mtThread);
if (agent_entry_name == NULL) {
return NULL;
}
strcpy(agent_entry_name, sym_name);
if (lib_name != NULL) {
strcat(agent_entry_name, "_");
strncat(agent_entry_name, lib_name, name_len);
}
return agent_entry_name;
}
int os::sleep(Thread* thread, jlong millis, bool interruptible) {
assert(thread == Thread::current(), "thread consistency check");
ParkEvent * const slp = thread->_SleepEvent ;
slp->reset() ;
OrderAccess::fence() ;
if (interruptible) {
jlong prevtime = javaTimeNanos();
for (;;) {
if (os::is_interrupted(thread, true)) {
return OS_INTRPT;
}
jlong newtime = javaTimeNanos();
if (newtime - prevtime < 0) {
// time moving backwards, should only happen if no monotonic clock
// not a guarantee() because JVM should not abort on kernel/glibc bugs
assert(!os::supports_monotonic_clock(), "unexpected time moving backwards detected in os::sleep(interruptible)");
} else {
millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
}
if (millis <= 0) {
return OS_OK;
}
prevtime = newtime;
{
assert(thread->is_Java_thread(), "sanity check");
JavaThread *jt = (JavaThread *) thread;
ThreadBlockInVM tbivm(jt);
OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
jt->set_suspend_equivalent();
// cleared by handle_special_suspend_equivalent_condition() or
// java_suspend_self() via check_and_wait_while_suspended()
slp->park(millis);
// were we externally suspended while we were waiting?
jt->check_and_wait_while_suspended();
}
}
} else {
OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
jlong prevtime = javaTimeNanos();
for (;;) {
// It'd be nice to avoid the back-to-back javaTimeNanos() calls on
// the 1st iteration ...
jlong newtime = javaTimeNanos();
if (newtime - prevtime < 0) {
// time moving backwards, should only happen if no monotonic clock
// not a guarantee() because JVM should not abort on kernel/glibc bugs
assert(!os::supports_monotonic_clock(), "unexpected time moving backwards detected on os::sleep(!interruptible)");
} else {
millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
}
if (millis <= 0) break ;
prevtime = newtime;
slp->park(millis);
}
return OS_OK ;
}
}
void os::naked_short_nanosleep(jlong ns) {
struct timespec req;
assert(ns > -1 && ns < NANOUNITS, "Un-interruptable sleep, short time use only");
req.tv_sec = 0;
req.tv_nsec = ns;
::nanosleep(&req, NULL);
return;
}
void os::naked_short_sleep(jlong ms) {
assert(ms < MILLIUNITS, "Un-interruptable sleep, short time use only");
os::naked_short_nanosleep(ms * (NANOUNITS / MILLIUNITS));
return;
}
////////////////////////////////////////////////////////////////////////////////
// interrupt support
void os::interrupt(Thread* thread) {
debug_only(Thread::check_for_dangling_thread_pointer(thread);)
OSThread* osthread = thread->osthread();
if (!osthread->interrupted()) {
osthread->set_interrupted(true);
// More than one thread can get here with the same value of osthread,
// resulting in multiple notifications. We do, however, want the store
// to interrupted() to be visible to other threads before we execute unpark().
OrderAccess::fence();
ParkEvent * const slp = thread->_SleepEvent ;
if (slp != NULL) slp->unpark() ;
}
// For JSR166. Unpark even if interrupt status already was set
if (thread->is_Java_thread())
((JavaThread*)thread)->parker()->unpark();
ParkEvent * ev = thread->_ParkEvent ;
if (ev != NULL) ev->unpark() ;
}
bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
debug_only(Thread::check_for_dangling_thread_pointer(thread);)
OSThread* osthread = thread->osthread();
bool interrupted = osthread->interrupted();
// NOTE that since there is no "lock" around the interrupt and
// is_interrupted operations, there is the possibility that the
// interrupted flag (in osThread) will be "false" but that the
// low-level events will be in the signaled state. This is
// intentional. The effect of this is that Object.wait() and
// LockSupport.park() will appear to have a spurious wakeup, which
// is allowed and not harmful, and the possibility is so rare that
// it is not worth the added complexity to add yet another lock.
// For the sleep event an explicit reset is performed on entry
// to os::sleep, so there is no early return. It has also been
// recommended not to put the interrupted flag into the "event"
// structure because it hides the issue.
if (interrupted && clear_interrupted) {
osthread->set_interrupted(false);
// consider thread->_SleepEvent->reset() ... optional optimization
}
return interrupted;
}
static const struct {
int sig; const char* name;
}
g_signal_info[] =
{
{ SIGABRT, "SIGABRT" },
#ifdef SIGAIO
{ SIGAIO, "SIGAIO" },
#endif
{ SIGALRM, "SIGALRM" },
#ifdef SIGALRM1
{ SIGALRM1, "SIGALRM1" },
#endif
{ SIGBUS, "SIGBUS" },
#ifdef SIGCANCEL
{ SIGCANCEL, "SIGCANCEL" },
#endif
{ SIGCHLD, "SIGCHLD" },
#ifdef SIGCLD
{ SIGCLD, "SIGCLD" },
#endif
{ SIGCONT, "SIGCONT" },
#ifdef SIGCPUFAIL
{ SIGCPUFAIL, "SIGCPUFAIL" },
#endif
#ifdef SIGDANGER
{ SIGDANGER, "SIGDANGER" },
#endif
#ifdef SIGDIL
{ SIGDIL, "SIGDIL" },
#endif
#ifdef SIGEMT
{ SIGEMT, "SIGEMT" },
#endif
{ SIGFPE, "SIGFPE" },
#ifdef SIGFREEZE
{ SIGFREEZE, "SIGFREEZE" },
#endif
#ifdef SIGGFAULT
{ SIGGFAULT, "SIGGFAULT" },
#endif
#ifdef SIGGRANT
{ SIGGRANT, "SIGGRANT" },
#endif
{ SIGHUP, "SIGHUP" },
{ SIGILL, "SIGILL" },
#ifdef SIGINFO
{ SIGINFO, "SIGINFO" },
#endif
{ SIGINT, "SIGINT" },
#ifdef SIGIO
{ SIGIO, "SIGIO" },
#endif
#ifdef SIGIOINT
{ SIGIOINT, "SIGIOINT" },
#endif
#ifdef SIGIOT
// SIGIOT is there for BSD compatibility, but on most Unices just a
// synonym for SIGABRT. The result should be "SIGABRT", not
// "SIGIOT".
#if (SIGIOT != SIGABRT )
{ SIGIOT, "SIGIOT" },
#endif
#endif
#ifdef SIGKAP
{ SIGKAP, "SIGKAP" },
#endif
{ SIGKILL, "SIGKILL" },
#ifdef SIGLOST
{ SIGLOST, "SIGLOST" },
#endif
#ifdef SIGLWP
{ SIGLWP, "SIGLWP" },
#endif
#ifdef SIGLWPTIMER
{ SIGLWPTIMER, "SIGLWPTIMER" },
#endif
#ifdef SIGMIGRATE
{ SIGMIGRATE, "SIGMIGRATE" },
#endif
#ifdef SIGMSG
{ SIGMSG, "SIGMSG" },
#endif
{ SIGPIPE, "SIGPIPE" },
#ifdef SIGPOLL
{ SIGPOLL, "SIGPOLL" },
#endif
#ifdef SIGPRE
{ SIGPRE, "SIGPRE" },
#endif
{ SIGPROF, "SIGPROF" },
#ifdef SIGPTY
{ SIGPTY, "SIGPTY" },
#endif
#ifdef SIGPWR
{ SIGPWR, "SIGPWR" },
#endif
{ SIGQUIT, "SIGQUIT" },
#ifdef SIGRECONFIG
{ SIGRECONFIG, "SIGRECONFIG" },
#endif
#ifdef SIGRECOVERY
{ SIGRECOVERY, "SIGRECOVERY" },
#endif
#ifdef SIGRESERVE
{ SIGRESERVE, "SIGRESERVE" },
#endif
#ifdef SIGRETRACT
{ SIGRETRACT, "SIGRETRACT" },
#endif
#ifdef SIGSAK
{ SIGSAK, "SIGSAK" },
#endif
{ SIGSEGV, "SIGSEGV" },
#ifdef SIGSOUND
{ SIGSOUND, "SIGSOUND" },
#endif
#ifdef SIGSTKFLT
{ SIGSTKFLT, "SIGSTKFLT" },
#endif
{ SIGSTOP, "SIGSTOP" },
{ SIGSYS, "SIGSYS" },
#ifdef SIGSYSERROR
{ SIGSYSERROR, "SIGSYSERROR" },
#endif
#ifdef SIGTALRM
{ SIGTALRM, "SIGTALRM" },
#endif
{ SIGTERM, "SIGTERM" },
#ifdef SIGTHAW
{ SIGTHAW, "SIGTHAW" },
#endif
{ SIGTRAP, "SIGTRAP" },
#ifdef SIGTSTP
{ SIGTSTP, "SIGTSTP" },
#endif
{ SIGTTIN, "SIGTTIN" },
{ SIGTTOU, "SIGTTOU" },
#ifdef SIGURG
{ SIGURG, "SIGURG" },
#endif
{ SIGUSR1, "SIGUSR1" },
{ SIGUSR2, "SIGUSR2" },
#ifdef SIGVIRT
{ SIGVIRT, "SIGVIRT" },
#endif
{ SIGVTALRM, "SIGVTALRM" },
#ifdef SIGWAITING
{ SIGWAITING, "SIGWAITING" },
#endif
#ifdef SIGWINCH
{ SIGWINCH, "SIGWINCH" },
#endif
#ifdef SIGWINDOW
{ SIGWINDOW, "SIGWINDOW" },
#endif
{ SIGXCPU, "SIGXCPU" },
{ SIGXFSZ, "SIGXFSZ" },
#ifdef SIGXRES
{ SIGXRES, "SIGXRES" },
#endif
{ -1, NULL }
};
// Returned string is a constant. For unknown signals "UNKNOWN" is returned.
const char* os::Posix::get_signal_name(int sig, char* out, size_t outlen) {
const char* ret = NULL;
#ifdef SIGRTMIN
if (sig >= SIGRTMIN && sig <= SIGRTMAX) {
if (sig == SIGRTMIN) {
ret = "SIGRTMIN";
} else if (sig == SIGRTMAX) {
ret = "SIGRTMAX";
} else {
jio_snprintf(out, outlen, "SIGRTMIN+%d", sig - SIGRTMIN);
return out;
}
}
#endif
if (sig > 0) {
for (int idx = 0; g_signal_info[idx].sig != -1; idx ++) {
if (g_signal_info[idx].sig == sig) {
ret = g_signal_info[idx].name;
break;
}
}
}
if (!ret) {
if (!is_valid_signal(sig)) {
ret = "INVALID";
} else {
ret = "UNKNOWN";
}
}
if (out && outlen > 0) {
strncpy(out, ret, outlen);
out[outlen - 1] = '\0';
}
return out;
}
int os::Posix::get_signal_number(const char* signal_name) {
char tmp[30];
const char* s = signal_name;
if (s[0] != 'S' || s[1] != 'I' || s[2] != 'G') {
jio_snprintf(tmp, sizeof(tmp), "SIG%s", signal_name);
s = tmp;
}
for (int idx = 0; g_signal_info[idx].sig != -1; idx ++) {
if (strcmp(g_signal_info[idx].name, s) == 0) {
return g_signal_info[idx].sig;
}
}
return -1;
}
int os::get_signal_number(const char* signal_name) {
return os::Posix::get_signal_number(signal_name);
}
// Returns true if signal number is valid.
bool os::Posix::is_valid_signal(int sig) {
// MacOS not really POSIX compliant: sigaddset does not return
// an error for invalid signal numbers. However, MacOS does not
// support real time signals and simply seems to have just 33
// signals with no holes in the signal range.
#ifdef __APPLE__
return sig >= 1 && sig < NSIG;
#else
// Use sigaddset to check for signal validity.
sigset_t set;
sigemptyset(&set);
if (sigaddset(&set, sig) == -1 && errno == EINVAL) {
return false;
}
return true;
#endif
}
bool os::Posix::is_sig_ignored(int sig) {
struct sigaction oact;
sigaction(sig, (struct sigaction*)NULL, &oact);
void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
: CAST_FROM_FN_PTR(void*, oact.sa_handler);
if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) {
return true;
} else {
return false;
}
}
// Returns:
// NULL for an invalid signal number
// "SIG<num>" for a valid but unknown signal number
// signal name otherwise.
const char* os::exception_name(int sig, char* buf, size_t size) {
if (!os::Posix::is_valid_signal(sig)) {
return NULL;
}
const char* const name = os::Posix::get_signal_name(sig, buf, size);
if (strcmp(name, "UNKNOWN") == 0) {
jio_snprintf(buf, size, "SIG%d", sig);
}
return buf;
}
#define NUM_IMPORTANT_SIGS 32
// Returns one-line short description of a signal set in a user provided buffer.
const char* os::Posix::describe_signal_set_short(const sigset_t* set, char* buffer, size_t buf_size) {
assert(buf_size == (NUM_IMPORTANT_SIGS + 1), "wrong buffer size");
// Note: for shortness, just print out the first 32. That should
// cover most of the useful ones, apart from realtime signals.
for (int sig = 1; sig <= NUM_IMPORTANT_SIGS; sig++) {
const int rc = sigismember(set, sig);
if (rc == -1 && errno == EINVAL) {
buffer[sig-1] = '?';
} else {
buffer[sig-1] = rc == 0 ? '0' : '1';
}
}
buffer[NUM_IMPORTANT_SIGS] = 0;
return buffer;
}
// Prints one-line description of a signal set.
void os::Posix::print_signal_set_short(outputStream* st, const sigset_t* set) {
char buf[NUM_IMPORTANT_SIGS + 1];
os::Posix::describe_signal_set_short(set, buf, sizeof(buf));
st->print("%s", buf);
}
// Writes one-line description of a combination of sigaction.sa_flags into a user
// provided buffer. Returns that buffer.
const char* os::Posix::describe_sa_flags(int flags, char* buffer, size_t size) {
char* p = buffer;
size_t remaining = size;
bool first = true;
int idx = 0;
assert(buffer, "invalid argument");
if (size == 0) {
return buffer;
}
strncpy(buffer, "none", size);
const struct {
// NB: i is an unsigned int here because SA_RESETHAND is on some
// systems 0x80000000, which is implicitly unsigned. Assignining
// it to an int field would be an overflow in unsigned-to-signed
// conversion.
unsigned int i;
const char* s;
} flaginfo [] = {
{ SA_NOCLDSTOP, "SA_NOCLDSTOP" },
{ SA_ONSTACK, "SA_ONSTACK" },
{ SA_RESETHAND, "SA_RESETHAND" },
{ SA_RESTART, "SA_RESTART" },
{ SA_SIGINFO, "SA_SIGINFO" },
{ SA_NOCLDWAIT, "SA_NOCLDWAIT" },
{ SA_NODEFER, "SA_NODEFER" },
#ifdef AIX
{ SA_ONSTACK, "SA_ONSTACK" },
{ SA_OLDSTYLE, "SA_OLDSTYLE" },
#endif
{ 0, NULL }
};
for (idx = 0; flaginfo[idx].s && remaining > 1; idx++) {
if (flags & flaginfo[idx].i) {
if (first) {
jio_snprintf(p, remaining, "%s", flaginfo[idx].s);
first = false;
} else {
jio_snprintf(p, remaining, "|%s", flaginfo[idx].s);
}
const size_t len = strlen(p);
p += len;
remaining -= len;
}
}
buffer[size - 1] = '\0';
return buffer;
}
// Prints one-line description of a combination of sigaction.sa_flags.
void os::Posix::print_sa_flags(outputStream* st, int flags) {
char buffer[0x100];
os::Posix::describe_sa_flags(flags, buffer, sizeof(buffer));
st->print("%s", buffer);
}
// Helper function for os::Posix::print_siginfo_...():
// return a textual description for signal code.
struct enum_sigcode_desc_t {
const char* s_name;
const char* s_desc;
};
static bool get_signal_code_description(const siginfo_t* si, enum_sigcode_desc_t* out) {
const struct {
int sig; int code; const char* s_code; const char* s_desc;
} t1 [] = {
{ SIGILL, ILL_ILLOPC, "ILL_ILLOPC", "Illegal opcode." },
{ SIGILL, ILL_ILLOPN, "ILL_ILLOPN", "Illegal operand." },
{ SIGILL, ILL_ILLADR, "ILL_ILLADR", "Illegal addressing mode." },
{ SIGILL, ILL_ILLTRP, "ILL_ILLTRP", "Illegal trap." },
{ SIGILL, ILL_PRVOPC, "ILL_PRVOPC", "Privileged opcode." },
{ SIGILL, ILL_PRVREG, "ILL_PRVREG", "Privileged register." },
{ SIGILL, ILL_COPROC, "ILL_COPROC", "Coprocessor error." },
{ SIGILL, ILL_BADSTK, "ILL_BADSTK", "Internal stack error." },
#if defined(IA64) && defined(LINUX)
{ SIGILL, ILL_BADIADDR, "ILL_BADIADDR", "Unimplemented instruction address" },
{ SIGILL, ILL_BREAK, "ILL_BREAK", "Application Break instruction" },
#endif
{ SIGFPE, FPE_INTDIV, "FPE_INTDIV", "Integer divide by zero." },
{ SIGFPE, FPE_INTOVF, "FPE_INTOVF", "Integer overflow." },
{ SIGFPE, FPE_FLTDIV, "FPE_FLTDIV", "Floating-point divide by zero." },
{ SIGFPE, FPE_FLTOVF, "FPE_FLTOVF", "Floating-point overflow." },
{ SIGFPE, FPE_FLTUND, "FPE_FLTUND", "Floating-point underflow." },
{ SIGFPE, FPE_FLTRES, "FPE_FLTRES", "Floating-point inexact result." },
{ SIGFPE, FPE_FLTINV, "FPE_FLTINV", "Invalid floating-point operation." },
{ SIGFPE, FPE_FLTSUB, "FPE_FLTSUB", "Subscript out of range." },
{ SIGSEGV, SEGV_MAPERR, "SEGV_MAPERR", "Address not mapped to object." },
{ SIGSEGV, SEGV_ACCERR, "SEGV_ACCERR", "Invalid permissions for mapped object." },
#ifdef AIX
// no explanation found what keyerr would be
{ SIGSEGV, SEGV_KEYERR, "SEGV_KEYERR", "key error" },
#endif
#if defined(IA64) && !defined(AIX)
{ SIGSEGV, SEGV_PSTKOVF, "SEGV_PSTKOVF", "Paragraph stack overflow" },
#endif
#if defined(__sparc) && defined(SOLARIS)
// define Solaris Sparc M7 ADI SEGV signals
#if !defined(SEGV_ACCADI)
#define SEGV_ACCADI 3
#endif
{ SIGSEGV, SEGV_ACCADI, "SEGV_ACCADI", "ADI not enabled for mapped object." },
#if !defined(SEGV_ACCDERR)
#define SEGV_ACCDERR 4
#endif
{ SIGSEGV, SEGV_ACCDERR, "SEGV_ACCDERR", "ADI disrupting exception." },
#if !defined(SEGV_ACCPERR)
#define SEGV_ACCPERR 5
#endif
{ SIGSEGV, SEGV_ACCPERR, "SEGV_ACCPERR", "ADI precise exception." },
#endif // defined(__sparc) && defined(SOLARIS)
{ SIGBUS, BUS_ADRALN, "BUS_ADRALN", "Invalid address alignment." },
{ SIGBUS, BUS_ADRERR, "BUS_ADRERR", "Nonexistent physical address." },
{ SIGBUS, BUS_OBJERR, "BUS_OBJERR", "Object-specific hardware error." },
{ SIGTRAP, TRAP_BRKPT, "TRAP_BRKPT", "Process breakpoint." },
{ SIGTRAP, TRAP_TRACE, "TRAP_TRACE", "Process trace trap." },
{ SIGCHLD, CLD_EXITED, "CLD_EXITED", "Child has exited." },
{ SIGCHLD, CLD_KILLED, "CLD_KILLED", "Child has terminated abnormally and did not create a core file." },
{ SIGCHLD, CLD_DUMPED, "CLD_DUMPED", "Child has terminated abnormally and created a core file." },
{ SIGCHLD, CLD_TRAPPED, "CLD_TRAPPED", "Traced child has trapped." },
{ SIGCHLD, CLD_STOPPED, "CLD_STOPPED", "Child has stopped." },
{ SIGCHLD, CLD_CONTINUED,"CLD_CONTINUED","Stopped child has continued." },
#ifdef SIGPOLL
{ SIGPOLL, POLL_OUT, "POLL_OUT", "Output buffers available." },
{ SIGPOLL, POLL_MSG, "POLL_MSG", "Input message available." },
{ SIGPOLL, POLL_ERR, "POLL_ERR", "I/O error." },
{ SIGPOLL, POLL_PRI, "POLL_PRI", "High priority input available." },
{ SIGPOLL, POLL_HUP, "POLL_HUP", "Device disconnected. [Option End]" },
#endif
{ -1, -1, NULL, NULL }
};
// Codes valid in any signal context.
const struct {
int code; const char* s_code; const char* s_desc;
} t2 [] = {
{ SI_USER, "SI_USER", "Signal sent by kill()." },
{ SI_QUEUE, "SI_QUEUE", "Signal sent by the sigqueue()." },
{ SI_TIMER, "SI_TIMER", "Signal generated by expiration of a timer set by timer_settime()." },
{ SI_ASYNCIO, "SI_ASYNCIO", "Signal generated by completion of an asynchronous I/O request." },
{ SI_MESGQ, "SI_MESGQ", "Signal generated by arrival of a message on an empty message queue." },
// Linux specific
#ifdef SI_TKILL
{ SI_TKILL, "SI_TKILL", "Signal sent by tkill (pthread_kill)" },
#endif
#ifdef SI_DETHREAD
{ SI_DETHREAD, "SI_DETHREAD", "Signal sent by execve() killing subsidiary threads" },
#endif
#ifdef SI_KERNEL
{ SI_KERNEL, "SI_KERNEL", "Signal sent by kernel." },
#endif
#ifdef SI_SIGIO
{ SI_SIGIO, "SI_SIGIO", "Signal sent by queued SIGIO" },
#endif
#ifdef AIX
{ SI_UNDEFINED, "SI_UNDEFINED","siginfo contains partial information" },
{ SI_EMPTY, "SI_EMPTY", "siginfo contains no useful information" },
#endif
#ifdef __sun
{ SI_NOINFO, "SI_NOINFO", "No signal information" },
{ SI_RCTL, "SI_RCTL", "kernel generated signal via rctl action" },
{ SI_LWP, "SI_LWP", "Signal sent via lwp_kill" },
#endif
{ -1, NULL, NULL }
};
const char* s_code = NULL;
const char* s_desc = NULL;
for (int i = 0; t1[i].sig != -1; i ++) {
if (t1[i].sig == si->si_signo && t1[i].code == si->si_code) {
s_code = t1[i].s_code;
s_desc = t1[i].s_desc;
break;
}
}
if (s_code == NULL) {
for (int i = 0; t2[i].s_code != NULL; i ++) {
if (t2[i].code == si->si_code) {
s_code = t2[i].s_code;
s_desc = t2[i].s_desc;
}
}
}
if (s_code == NULL) {
out->s_name = "unknown";
out->s_desc = "unknown";
return false;
}
out->s_name = s_code;
out->s_desc = s_desc;
return true;
}
bool os::signal_sent_by_kill(const void* siginfo) {
const siginfo_t* const si = (const siginfo_t*)siginfo;
return si->si_code == SI_USER || si->si_code == SI_QUEUE
#ifdef SI_TKILL
|| si->si_code == SI_TKILL
#endif
;
}
void os::print_siginfo(outputStream* os, const void* si0) {
const siginfo_t* const si = (const siginfo_t*) si0;
char buf[20];
os->print("siginfo:");
if (!si) {
os->print(" <null>");
return;
}
const int sig = si->si_signo;
os->print(" si_signo: %d (%s)", sig, os::Posix::get_signal_name(sig, buf, sizeof(buf)));
enum_sigcode_desc_t ed;
get_signal_code_description(si, &ed);
os->print(", si_code: %d (%s)", si->si_code, ed.s_name);
if (si->si_errno) {
os->print(", si_errno: %d", si->si_errno);
}
// Output additional information depending on the signal code.
// Note: Many implementations lump si_addr, si_pid, si_uid etc. together as unions,
// so it depends on the context which member to use. For synchronous error signals,
// we print si_addr, unless the signal was sent by another process or thread, in
// which case we print out pid or tid of the sender.
if (signal_sent_by_kill(si)) {
const pid_t pid = si->si_pid;
os->print(", si_pid: %ld", (long) pid);
if (IS_VALID_PID(pid)) {
const pid_t me = getpid();
if (me == pid) {
os->print(" (current process)");
}
} else {
os->print(" (invalid)");
}
os->print(", si_uid: %ld", (long) si->si_uid);
if (sig == SIGCHLD) {
os->print(", si_status: %d", si->si_status);
}
} else if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
sig == SIGTRAP || sig == SIGFPE) {
os->print(", si_addr: " PTR_FORMAT, p2i(si->si_addr));
#ifdef SIGPOLL
} else if (sig == SIGPOLL) {
os->print(", si_band: %ld", si->si_band);
#endif
}
}
bool os::signal_thread(Thread* thread, int sig, const char* reason) {
OSThread* osthread = thread->osthread();
if (osthread) {
#if defined (SOLARIS)
// Note: we cannot use pthread_kill on Solaris - not because
// its missing, but because we do not have the pthread_t id.
int status = thr_kill(osthread->thread_id(), sig);
#else
int status = pthread_kill(osthread->pthread_id(), sig);
#endif
if (status == 0) {
Events::log(Thread::current(), "sent signal %d to Thread " INTPTR_FORMAT " because %s.",
sig, p2i(thread), reason);
return true;
}
}
return false;
}
int os::Posix::unblock_thread_signal_mask(const sigset_t *set) {
return pthread_sigmask(SIG_UNBLOCK, set, NULL);
}
address os::Posix::ucontext_get_pc(const ucontext_t* ctx) {
#if defined(AIX)
return Aix::ucontext_get_pc(ctx);
#elif defined(BSD)
return Bsd::ucontext_get_pc(ctx);
#elif defined(LINUX)
return Linux::ucontext_get_pc(ctx);
#elif defined(SOLARIS)
return Solaris::ucontext_get_pc(ctx);
#else
VMError::report_and_die("unimplemented ucontext_get_pc");
#endif
}
void os::Posix::ucontext_set_pc(ucontext_t* ctx, address pc) {
#if defined(AIX)
Aix::ucontext_set_pc(ctx, pc);
#elif defined(BSD)
Bsd::ucontext_set_pc(ctx, pc);
#elif defined(LINUX)
Linux::ucontext_set_pc(ctx, pc);
#elif defined(SOLARIS)
Solaris::ucontext_set_pc(ctx, pc);
#else
VMError::report_and_die("unimplemented ucontext_get_pc");
#endif
}
char* os::Posix::describe_pthread_attr(char* buf, size_t buflen, const pthread_attr_t* attr) {
size_t stack_size = 0;
size_t guard_size = 0;
int detachstate = 0;
pthread_attr_getstacksize(attr, &stack_size);
pthread_attr_getguardsize(attr, &guard_size);
// Work around linux NPTL implementation error, see also os::create_thread() in os_linux.cpp.
LINUX_ONLY(stack_size -= guard_size);
pthread_attr_getdetachstate(attr, &detachstate);
jio_snprintf(buf, buflen, "stacksize: " SIZE_FORMAT "k, guardsize: " SIZE_FORMAT "k, %s",
stack_size / 1024, guard_size / 1024,
(detachstate == PTHREAD_CREATE_DETACHED ? "detached" : "joinable"));
return buf;
}
char* os::Posix::realpath(const char* filename, char* outbuf, size_t outbuflen) {
if (filename == NULL || outbuf == NULL || outbuflen < 1) {
assert(false, "os::Posix::realpath: invalid arguments.");
errno = EINVAL;
return NULL;
}
char* result = NULL;
// This assumes platform realpath() is implemented according to POSIX.1-2008.
// POSIX.1-2008 allows to specify NULL for the output buffer, in which case
// output buffer is dynamically allocated and must be ::free()'d by the caller.
char* p = ::realpath(filename, NULL);
if (p != NULL) {
if (strlen(p) < outbuflen) {
strcpy(outbuf, p);
result = outbuf;
} else {
errno = ENAMETOOLONG;
}
::free(p); // *not* os::free
} else {
// Fallback for platforms struggling with modern Posix standards (AIX 5.3, 6.1). If realpath
// returns EINVAL, this may indicate that realpath is not POSIX.1-2008 compatible and
// that it complains about the NULL we handed down as user buffer.
// In this case, use the user provided buffer but at least check whether realpath caused
// a memory overwrite.
if (errno == EINVAL) {
outbuf[outbuflen - 1] = '\0';
p = ::realpath(filename, outbuf);
if (p != NULL) {
guarantee(outbuf[outbuflen - 1] == '\0', "realpath buffer overwrite detected.");
result = p;
}
}
}
return result;
}
int os::stat(const char *path, struct stat *sbuf) {
return ::stat(path, sbuf);
}
char * os::native_path(char *path) {
return path;
}
// Check minimum allowable stack sizes for thread creation and to initialize
// the java system classes, including StackOverflowError - depends on page
// size.
// The space needed for frames during startup is platform dependent. It
// depends on word size, platform calling conventions, C frame layout and
// interpreter/C1/C2 design decisions. Therefore this is given in a
// platform (os/cpu) dependent constant.
// To this, space for guard mechanisms is added, which depends on the
// page size which again depends on the concrete system the VM is running
// on. Space for libc guard pages is not included in this size.
jint os::Posix::set_minimum_stack_sizes() {
size_t os_min_stack_allowed = SOLARIS_ONLY(thr_min_stack()) NOT_SOLARIS(PTHREAD_STACK_MIN);
_java_thread_min_stack_allowed = _java_thread_min_stack_allowed +
JavaThread::stack_guard_zone_size() +
JavaThread::stack_shadow_zone_size();
_java_thread_min_stack_allowed = align_up(_java_thread_min_stack_allowed, vm_page_size());
_java_thread_min_stack_allowed = MAX2(_java_thread_min_stack_allowed, os_min_stack_allowed);
size_t stack_size_in_bytes = ThreadStackSize * K;
if (stack_size_in_bytes != 0 &&
stack_size_in_bytes < _java_thread_min_stack_allowed) {
// The '-Xss' and '-XX:ThreadStackSize=N' options both set
// ThreadStackSize so we go with "Java thread stack size" instead
// of "ThreadStackSize" to be more friendly.
tty->print_cr("\nThe Java thread stack size specified is too small. "
"Specify at least " SIZE_FORMAT "k",
_java_thread_min_stack_allowed / K);
return JNI_ERR;
}
// Make the stack size a multiple of the page size so that
// the yellow/red zones can be guarded.
JavaThread::set_stack_size_at_create(align_up(stack_size_in_bytes, vm_page_size()));
// Reminder: a compiler thread is a Java thread.
_compiler_thread_min_stack_allowed = _compiler_thread_min_stack_allowed +
JavaThread::stack_guard_zone_size() +
JavaThread::stack_shadow_zone_size();
_compiler_thread_min_stack_allowed = align_up(_compiler_thread_min_stack_allowed, vm_page_size());
_compiler_thread_min_stack_allowed = MAX2(_compiler_thread_min_stack_allowed, os_min_stack_allowed);
stack_size_in_bytes = CompilerThreadStackSize * K;
if (stack_size_in_bytes != 0 &&
stack_size_in_bytes < _compiler_thread_min_stack_allowed) {
tty->print_cr("\nThe CompilerThreadStackSize specified is too small. "
"Specify at least " SIZE_FORMAT "k",
_compiler_thread_min_stack_allowed / K);
return JNI_ERR;
}
_vm_internal_thread_min_stack_allowed = align_up(_vm_internal_thread_min_stack_allowed, vm_page_size());
_vm_internal_thread_min_stack_allowed = MAX2(_vm_internal_thread_min_stack_allowed, os_min_stack_allowed);
stack_size_in_bytes = VMThreadStackSize * K;
if (stack_size_in_bytes != 0 &&
stack_size_in_bytes < _vm_internal_thread_min_stack_allowed) {
tty->print_cr("\nThe VMThreadStackSize specified is too small. "
"Specify at least " SIZE_FORMAT "k",
_vm_internal_thread_min_stack_allowed / K);
return JNI_ERR;
}
return JNI_OK;
}
// Called when creating the thread. The minimum stack sizes have already been calculated
size_t os::Posix::get_initial_stack_size(ThreadType thr_type, size_t req_stack_size) {
size_t stack_size;
if (req_stack_size == 0) {
stack_size = default_stack_size(thr_type);
} else {
stack_size = req_stack_size;
}
switch (thr_type) {
case os::java_thread:
// Java threads use ThreadStackSize which default value can be
// changed with the flag -Xss
if (req_stack_size == 0 && JavaThread::stack_size_at_create() > 0) {
// no requested size and we have a more specific default value
stack_size = JavaThread::stack_size_at_create();
}
stack_size = MAX2(stack_size,
_java_thread_min_stack_allowed);
break;
case os::compiler_thread:
if (req_stack_size == 0 && CompilerThreadStackSize > 0) {
// no requested size and we have a more specific default value
stack_size = (size_t)(CompilerThreadStackSize * K);
}
stack_size = MAX2(stack_size,
_compiler_thread_min_stack_allowed);
break;
case os::vm_thread:
case os::pgc_thread:
case os::cgc_thread:
case os::watcher_thread:
default: // presume the unknown thr_type is a VM internal
if (req_stack_size == 0 && VMThreadStackSize > 0) {
// no requested size and we have a more specific default value
stack_size = (size_t)(VMThreadStackSize * K);
}
stack_size = MAX2(stack_size,
_vm_internal_thread_min_stack_allowed);
break;
}
// pthread_attr_setstacksize() may require that the size be rounded up to the OS page size.
// Be careful not to round up to 0. Align down in that case.
if (stack_size <= SIZE_MAX - vm_page_size()) {
stack_size = align_up(stack_size, vm_page_size());
} else {
stack_size = align_down(stack_size, vm_page_size());
}
return stack_size;
}
bool os::Posix::is_root(uid_t uid){
return ROOT_UID == uid;
}
bool os::Posix::matches_effective_uid_or_root(uid_t uid) {
return is_root(uid) || geteuid() == uid;
}
bool os::Posix::matches_effective_uid_and_gid_or_root(uid_t uid, gid_t gid) {
return is_root(uid) || (geteuid() == uid && getegid() == gid);
}
Thread* os::ThreadCrashProtection::_protected_thread = NULL;
os::ThreadCrashProtection* os::ThreadCrashProtection::_crash_protection = NULL;
volatile intptr_t os::ThreadCrashProtection::_crash_mux = 0;
os::ThreadCrashProtection::ThreadCrashProtection() {
}
/*
* See the caveats for this class in os_posix.hpp
* Protects the callback call so that SIGSEGV / SIGBUS jumps back into this
* method and returns false. If none of the signals are raised, returns true.
* The callback is supposed to provide the method that should be protected.
*/
bool os::ThreadCrashProtection::call(os::CrashProtectionCallback& cb) {
sigset_t saved_sig_mask;
Thread::muxAcquire(&_crash_mux, "CrashProtection");
_protected_thread = Thread::current_or_null();
assert(_protected_thread != NULL, "Cannot crash protect a NULL thread");
// we cannot rely on sigsetjmp/siglongjmp to save/restore the signal mask
// since on at least some systems (OS X) siglongjmp will restore the mask
// for the process, not the thread
pthread_sigmask(0, NULL, &saved_sig_mask);
if (sigsetjmp(_jmpbuf, 0) == 0) {
// make sure we can see in the signal handler that we have crash protection
// installed
_crash_protection = this;
cb.call();
// and clear the crash protection
_crash_protection = NULL;
_protected_thread = NULL;
Thread::muxRelease(&_crash_mux);
return true;
}
// this happens when we siglongjmp() back
pthread_sigmask(SIG_SETMASK, &saved_sig_mask, NULL);
_crash_protection = NULL;
_protected_thread = NULL;
Thread::muxRelease(&_crash_mux);
return false;
}
void os::ThreadCrashProtection::restore() {
assert(_crash_protection != NULL, "must have crash protection");
siglongjmp(_jmpbuf, 1);
}
void os::ThreadCrashProtection::check_crash_protection(int sig,
Thread* thread) {
if (thread != NULL &&
thread == _protected_thread &&
_crash_protection != NULL) {
if (sig == SIGSEGV || sig == SIGBUS) {
_crash_protection->restore();
}
}
}
// Shared pthread_mutex/cond based PlatformEvent implementation.
// Not currently usable by Solaris.
#ifndef SOLARIS
// Shared condattr object for use with relative timed-waits. Will be associated
// with CLOCK_MONOTONIC if available to avoid issues with time-of-day changes,
// but otherwise whatever default is used by the platform - generally the
// time-of-day clock.
static pthread_condattr_t _condAttr[1];
// Shared mutexattr to explicitly set the type to PTHREAD_MUTEX_NORMAL as not
// all systems (e.g. FreeBSD) map the default to "normal".
static pthread_mutexattr_t _mutexAttr[1];
// common basic initialization that is always supported
static void pthread_init_common(void) {
int status;
if ((status = pthread_condattr_init(_condAttr)) != 0) {
fatal("pthread_condattr_init: %s", os::strerror(status));
}
if ((status = pthread_mutexattr_init(_mutexAttr)) != 0) {
fatal("pthread_mutexattr_init: %s", os::strerror(status));
}
if ((status = pthread_mutexattr_settype(_mutexAttr, PTHREAD_MUTEX_NORMAL)) != 0) {
fatal("pthread_mutexattr_settype: %s", os::strerror(status));
}
}
#ifndef SOLARIS
sigset_t sigs;
struct sigaction sigact[NSIG];
struct sigaction* os::Posix::get_preinstalled_handler(int sig) {
if (sigismember(&sigs, sig)) {
return &sigact[sig];
}
return NULL;
}
void os::Posix::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
assert(sig > 0 && sig < NSIG, "vm signal out of expected range");
sigact[sig] = oldAct;
sigaddset(&sigs, sig);
}
#endif
// Not all POSIX types and API's are available on all notionally "posix"
// platforms. If we have build-time support then we will check for actual
// runtime support via dlopen/dlsym lookup. This allows for running on an
// older OS version compared to the build platform. But if there is no
// build time support then there cannot be any runtime support as we do not
// know what the runtime types would be (for example clockid_t might be an
// int or int64_t).
//
#ifdef SUPPORTS_CLOCK_MONOTONIC
// This means we have clockid_t, clock_gettime et al and CLOCK_MONOTONIC
static int (*_clock_gettime)(clockid_t, struct timespec *);
static int (*_pthread_condattr_setclock)(pthread_condattr_t *, clockid_t);
static bool _use_clock_monotonic_condattr;
// Determine what POSIX API's are present and do appropriate
// configuration.
void os::Posix::init(void) {
// NOTE: no logging available when this is called. Put logging
// statements in init_2().
// Copied from os::Linux::clock_init(). The duplication is temporary.
// 1. Check for CLOCK_MONOTONIC support.
void* handle = NULL;
// For linux we need librt, for other OS we can find
// this function in regular libc.
#ifdef NEEDS_LIBRT
// We do dlopen's in this particular order due to bug in linux
// dynamic loader (see 6348968) leading to crash on exit.
handle = dlopen("librt.so.1", RTLD_LAZY);
if (handle == NULL) {
handle = dlopen("librt.so", RTLD_LAZY);
}
#endif
if (handle == NULL) {
handle = RTLD_DEFAULT;
}
_clock_gettime = NULL;
int (*clock_getres_func)(clockid_t, struct timespec*) =
(int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
int (*clock_gettime_func)(clockid_t, struct timespec*) =
(int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
if (clock_getres_func != NULL && clock_gettime_func != NULL) {
// We assume that if both clock_gettime and clock_getres support
// CLOCK_MONOTONIC then the OS provides true high-res monotonic clock.
struct timespec res;
struct timespec tp;
if (clock_getres_func(CLOCK_MONOTONIC, &res) == 0 &&
clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
// Yes, monotonic clock is supported.
_clock_gettime = clock_gettime_func;
} else {
#ifdef NEEDS_LIBRT
// Close librt if there is no monotonic clock.
if (handle != RTLD_DEFAULT) {
dlclose(handle);
}
#endif
}
}
// 2. Check for pthread_condattr_setclock support.
_pthread_condattr_setclock = NULL;
// libpthread is already loaded.
int (*condattr_setclock_func)(pthread_condattr_t*, clockid_t) =
(int (*)(pthread_condattr_t*, clockid_t))dlsym(RTLD_DEFAULT,
"pthread_condattr_setclock");
if (condattr_setclock_func != NULL) {
_pthread_condattr_setclock = condattr_setclock_func;
}
// Now do general initialization.
pthread_init_common();
int status;
if (_pthread_condattr_setclock != NULL && _clock_gettime != NULL) {
if ((status = _pthread_condattr_setclock(_condAttr, CLOCK_MONOTONIC)) != 0) {
if (status == EINVAL) {
_use_clock_monotonic_condattr = false;
warning("Unable to use monotonic clock with relative timed-waits" \
" - changes to the time-of-day clock may have adverse affects");
} else {
fatal("pthread_condattr_setclock: %s", os::strerror(status));
}
} else {
_use_clock_monotonic_condattr = true;
}
} else {
_use_clock_monotonic_condattr = false;
}
}
void os::Posix::init_2(void) {
log_info(os)("Use of CLOCK_MONOTONIC is%s supported",
(_clock_gettime != NULL ? "" : " not"));
log_info(os)("Use of pthread_condattr_setclock is%s supported",
(_pthread_condattr_setclock != NULL ? "" : " not"));
log_info(os)("Relative timed-wait using pthread_cond_timedwait is associated with %s",
_use_clock_monotonic_condattr ? "CLOCK_MONOTONIC" : "the default clock");
#ifndef SOLARIS
sigemptyset(&sigs);
#endif
}
#else // !SUPPORTS_CLOCK_MONOTONIC
void os::Posix::init(void) {
pthread_init_common();
}
void os::Posix::init_2(void) {
log_info(os)("Use of CLOCK_MONOTONIC is not supported");
log_info(os)("Use of pthread_condattr_setclock is not supported");
log_info(os)("Relative timed-wait using pthread_cond_timedwait is associated with the default clock");
#ifndef SOLARIS
sigemptyset(&sigs);
#endif
}
#endif // SUPPORTS_CLOCK_MONOTONIC
os::PlatformEvent::PlatformEvent() {
int status = pthread_cond_init(_cond, _condAttr);
assert_status(status == 0, status, "cond_init");
status = pthread_mutex_init(_mutex, _mutexAttr);
assert_status(status == 0, status, "mutex_init");
_event = 0;
_nParked = 0;
}
// Utility to convert the given timeout to an absolute timespec
// (based on the appropriate clock) to use with pthread_cond_timewait.
// The clock queried here must be the clock used to manage the
// timeout of the condition variable.
//
// The passed in timeout value is either a relative time in nanoseconds
// or an absolute time in milliseconds. A relative timeout will be
// associated with CLOCK_MONOTONIC if available; otherwise, or if absolute,
// the default time-of-day clock will be used.
// Given time is a 64-bit value and the time_t used in the timespec is
// sometimes a signed-32-bit value we have to watch for overflow if times
// way in the future are given. Further on Solaris versions
// prior to 10 there is a restriction (see cond_timedwait) that the specified
// number of seconds, in abstime, is less than current_time + 100000000.
// As it will be over 20 years before "now + 100000000" will overflow we can
// ignore overflow and just impose a hard-limit on seconds using the value
// of "now + 100000000". This places a limit on the timeout of about 3.17
// years from "now".
//
#define MAX_SECS 100000000
// Calculate a new absolute time that is "timeout" nanoseconds from "now".
// "unit" indicates the unit of "now_part_sec" (may be nanos or micros depending
// on which clock is being used).
static void calc_rel_time(timespec* abstime, jlong timeout, jlong now_sec,
jlong now_part_sec, jlong unit) {
time_t max_secs = now_sec + MAX_SECS;
jlong seconds = timeout / NANOUNITS;
timeout %= NANOUNITS; // remaining nanos
if (seconds >= MAX_SECS) {
// More seconds than we can add, so pin to max_secs.
abstime->tv_sec = max_secs;
abstime->tv_nsec = 0;
} else {
abstime->tv_sec = now_sec + seconds;
long nanos = (now_part_sec * (NANOUNITS / unit)) + timeout;
if (nanos >= NANOUNITS) { // overflow
abstime->tv_sec += 1;
nanos -= NANOUNITS;
}
abstime->tv_nsec = nanos;
}
}
// Unpack the given deadline in milliseconds since the epoch, into the given timespec.
// The current time in seconds is also passed in to enforce an upper bound as discussed above.
static void unpack_abs_time(timespec* abstime, jlong deadline, jlong now_sec) {
time_t max_secs = now_sec + MAX_SECS;
jlong seconds = deadline / MILLIUNITS;
jlong millis = deadline % MILLIUNITS;
if (seconds >= max_secs) {
// Absolute seconds exceeds allowed max, so pin to max_secs.
abstime->tv_sec = max_secs;
abstime->tv_nsec = 0;
} else {
abstime->tv_sec = seconds;
abstime->tv_nsec = millis * (NANOUNITS / MILLIUNITS);
}
}
static void to_abstime(timespec* abstime, jlong timeout, bool isAbsolute) {
DEBUG_ONLY(int max_secs = MAX_SECS;)
if (timeout < 0) {
timeout = 0;
}
#ifdef SUPPORTS_CLOCK_MONOTONIC
if (_use_clock_monotonic_condattr && !isAbsolute) {
struct timespec now;
int status = _clock_gettime(CLOCK_MONOTONIC, &now);
assert_status(status == 0, status, "clock_gettime");
calc_rel_time(abstime, timeout, now.tv_sec, now.tv_nsec, NANOUNITS);
DEBUG_ONLY(max_secs += now.tv_sec;)
} else {
#else
{ // Match the block scope.
#endif // SUPPORTS_CLOCK_MONOTONIC
// Time-of-day clock is all we can reliably use.
struct timeval now;
int status = gettimeofday(&now, NULL);
assert_status(status == 0, errno, "gettimeofday");
if (isAbsolute) {
unpack_abs_time(abstime, timeout, now.tv_sec);
} else {
calc_rel_time(abstime, timeout, now.tv_sec, now.tv_usec, MICROUNITS);
}
DEBUG_ONLY(max_secs += now.tv_sec;)
}
assert(abstime->tv_sec >= 0, "tv_sec < 0");
assert(abstime->tv_sec <= max_secs, "tv_sec > max_secs");
assert(abstime->tv_nsec >= 0, "tv_nsec < 0");
assert(abstime->tv_nsec < NANOUNITS, "tv_nsec >= NANOUNITS");
}
// PlatformEvent
//
// Assumption:
// Only one parker can exist on an event, which is why we allocate
// them per-thread. Multiple unparkers can coexist.
//
// _event serves as a restricted-range semaphore.
// -1 : thread is blocked, i.e. there is a waiter
// 0 : neutral: thread is running or ready,
// could have been signaled after a wait started
// 1 : signaled - thread is running or ready
//
// Having three states allows for some detection of bad usage - see
// comments on unpark().
void os::PlatformEvent::park() { // AKA "down()"
// Transitions for _event:
// -1 => -1 : illegal
// 1 => 0 : pass - return immediately
// 0 => -1 : block; then set _event to 0 before returning
// Invariant: Only the thread associated with the PlatformEvent
// may call park().
assert(_nParked == 0, "invariant");
int v;
// atomically decrement _event
for (;;) {
v = _event;
if (Atomic::cmpxchg(v - 1, &_event, v) == v) break;
}
guarantee(v >= 0, "invariant");
if (v == 0) { // Do this the hard way by blocking ...
int status = pthread_mutex_lock(_mutex);
assert_status(status == 0, status, "mutex_lock");
guarantee(_nParked == 0, "invariant");
++_nParked;
while (_event < 0) {
// OS-level "spurious wakeups" are ignored
status = pthread_cond_wait(_cond, _mutex);
assert_status(status == 0, status, "cond_wait");
}
--_nParked;
_event = 0;
status = pthread_mutex_unlock(_mutex);
assert_status(status == 0, status, "mutex_unlock");
// Paranoia to ensure our locked and lock-free paths interact
// correctly with each other.
OrderAccess::fence();
}
guarantee(_event >= 0, "invariant");
}
int os::PlatformEvent::park(jlong millis) {
// Transitions for _event:
// -1 => -1 : illegal
// 1 => 0 : pass - return immediately
// 0 => -1 : block; then set _event to 0 before returning
// Invariant: Only the thread associated with the Event/PlatformEvent
// may call park().
assert(_nParked == 0, "invariant");
int v;
// atomically decrement _event
for (;;) {
v = _event;
if (Atomic::cmpxchg(v - 1, &_event, v) == v) break;
}
guarantee(v >= 0, "invariant");
if (v == 0) { // Do this the hard way by blocking ...
struct timespec abst;
// We have to watch for overflow when converting millis to nanos,
// but if millis is that large then we will end up limiting to
// MAX_SECS anyway, so just do that here.
if (millis / MILLIUNITS > MAX_SECS) {
millis = jlong(MAX_SECS) * MILLIUNITS;
}
to_abstime(&abst, millis * (NANOUNITS / MILLIUNITS), false);
int ret = OS_TIMEOUT;
int status = pthread_mutex_lock(_mutex);
assert_status(status == 0, status, "mutex_lock");
guarantee(_nParked == 0, "invariant");
++_nParked;
while (_event < 0) {
status = pthread_cond_timedwait(_cond, _mutex, &abst);
assert_status(status == 0 || status == ETIMEDOUT,
status, "cond_timedwait");
// OS-level "spurious wakeups" are ignored unless the archaic
// FilterSpuriousWakeups is set false. That flag should be obsoleted.
if (!FilterSpuriousWakeups) break;
if (status == ETIMEDOUT) break;
}
--_nParked;
if (_event >= 0) {
ret = OS_OK;
}
_event = 0;
status = pthread_mutex_unlock(_mutex);
assert_status(status == 0, status, "mutex_unlock");
// Paranoia to ensure our locked and lock-free paths interact
// correctly with each other.
OrderAccess::fence();
return ret;
}
return OS_OK;
}
void os::PlatformEvent::unpark() {
// Transitions for _event:
// 0 => 1 : just return
// 1 => 1 : just return
// -1 => either 0 or 1; must signal target thread
// That is, we can safely transition _event from -1 to either
// 0 or 1.
// See also: "Semaphores in Plan 9" by Mullender & Cox
//
// Note: Forcing a transition from "-1" to "1" on an unpark() means
// that it will take two back-to-back park() calls for the owning
// thread to block. This has the benefit of forcing a spurious return
// from the first park() call after an unpark() call which will help
// shake out uses of park() and unpark() without checking state conditions
// properly. This spurious return doesn't manifest itself in any user code
// but only in the correctly written condition checking loops of ObjectMonitor,
// Mutex/Monitor, Thread::muxAcquire and os::sleep
if (Atomic::xchg(1, &_event) >= 0) return;
int status = pthread_mutex_lock(_mutex);
assert_status(status == 0, status, "mutex_lock");
int anyWaiters = _nParked;
assert(anyWaiters == 0 || anyWaiters == 1, "invariant");
status = pthread_mutex_unlock(_mutex);
assert_status(status == 0, status, "mutex_unlock");
// Note that we signal() *after* dropping the lock for "immortal" Events.
// This is safe and avoids a common class of futile wakeups. In rare
// circumstances this can cause a thread to return prematurely from
// cond_{timed}wait() but the spurious wakeup is benign and the victim
// will simply re-test the condition and re-park itself.
// This provides particular benefit if the underlying platform does not
// provide wait morphing.
if (anyWaiters != 0) {
status = pthread_cond_signal(_cond);
assert_status(status == 0, status, "cond_signal");
}
}
// JSR166 support
os::PlatformParker::PlatformParker() {
int status;
status = pthread_cond_init(&_cond[REL_INDEX], _condAttr);
assert_status(status == 0, status, "cond_init rel");
status = pthread_cond_init(&_cond[ABS_INDEX], NULL);
assert_status(status == 0, status, "cond_init abs");
status = pthread_mutex_init(_mutex, _mutexAttr);
assert_status(status == 0, status, "mutex_init");
_cur_index = -1; // mark as unused
}
// Parker::park decrements count if > 0, else does a condvar wait. Unpark
// sets count to 1 and signals condvar. Only one thread ever waits
// on the condvar. Contention seen when trying to park implies that someone
// is unparking you, so don't wait. And spurious returns are fine, so there
// is no need to track notifications.
void Parker::park(bool isAbsolute, jlong time) {
// Optional fast-path check:
// Return immediately if a permit is available.
// We depend on Atomic::xchg() having full barrier semantics
// since we are doing a lock-free update to _counter.
if (Atomic::xchg(0, &_counter) > 0) return;
Thread* thread = Thread::current();
assert(thread->is_Java_thread(), "Must be JavaThread");
JavaThread *jt = (JavaThread *)thread;
// Optional optimization -- avoid state transitions if there's
// an interrupt pending.
if (Thread::is_interrupted(thread, false)) {
return;
}
// Next, demultiplex/decode time arguments
struct timespec absTime;
if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all
return;
}
if (time > 0) {
to_abstime(&absTime, time, isAbsolute);
}
// Enter safepoint region
// Beware of deadlocks such as 6317397.
// The per-thread Parker:: mutex is a classic leaf-lock.
// In particular a thread must never block on the Threads_lock while
// holding the Parker:: mutex. If safepoints are pending both the
// the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
ThreadBlockInVM tbivm(jt);
// Don't wait if cannot get lock since interference arises from
// unparking. Also re-check interrupt before trying wait.
if (Thread::is_interrupted(thread, false) ||
pthread_mutex_trylock(_mutex) != 0) {
return;
}
int status;
if (_counter > 0) { // no wait needed
_counter = 0;
status = pthread_mutex_unlock(_mutex);
assert_status(status == 0, status, "invariant");
// Paranoia to ensure our locked and lock-free paths interact
// correctly with each other and Java-level accesses.
OrderAccess::fence();
return;
}
OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
jt->set_suspend_equivalent();
// cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
assert(_cur_index == -1, "invariant");
if (time == 0) {
_cur_index = REL_INDEX; // arbitrary choice when not timed
status = pthread_cond_wait(&_cond[_cur_index], _mutex);
assert_status(status == 0, status, "cond_timedwait");
}
else {
_cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
status = pthread_cond_timedwait(&_cond[_cur_index], _mutex, &absTime);
assert_status(status == 0 || status == ETIMEDOUT,
status, "cond_timedwait");
}
_cur_index = -1;
_counter = 0;
status = pthread_mutex_unlock(_mutex);
assert_status(status == 0, status, "invariant");
// Paranoia to ensure our locked and lock-free paths interact
// correctly with each other and Java-level accesses.
OrderAccess::fence();
// If externally suspended while waiting, re-suspend
if (jt->handle_special_suspend_equivalent_condition()) {
jt->java_suspend_self();
}
}
void Parker::unpark() {
int status = pthread_mutex_lock(_mutex);
assert_status(status == 0, status, "invariant");
const int s = _counter;
_counter = 1;
// must capture correct index before unlocking
int index = _cur_index;
status = pthread_mutex_unlock(_mutex);
assert_status(status == 0, status, "invariant");
// Note that we signal() *after* dropping the lock for "immortal" Events.
// This is safe and avoids a common class of futile wakeups. In rare
// circumstances this can cause a thread to return prematurely from
// cond_{timed}wait() but the spurious wakeup is benign and the victim
// will simply re-test the condition and re-park itself.
// This provides particular benefit if the underlying platform does not
// provide wait morphing.
if (s < 1 && index != -1) {
// thread is definitely parked
status = pthread_cond_signal(&_cond[index]);
assert_status(status == 0, status, "invariant");
}
}
#endif // !SOLARIS