Google Git
Sign in
android / platform / external / rust / crates / grpcio-sys / refs/heads/android-s-beta-4 / . / grpc / src / core / lib / iomgr / ev_epollex_linux.cc
blob: 72d7da76ba5c9d80b5a67fd21cc7465e75af4aa0 [file] [log] [blame]
/*
*
* Copyright 2017 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#include <grpc/support/port_platform.h>
#include "src/core/lib/iomgr/port.h"
#include <grpc/support/log.h>
/* This polling engine is only relevant on linux kernels supporting epoll() */
#ifdef GRPC_LINUX_EPOLL_CREATE1
#include "src/core/lib/iomgr/ev_epollex_linux.h"
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <poll.h>
#include <pthread.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <string>
#include "absl/container/inlined_vector.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/str_format.h"
#include <grpc/support/alloc.h>
#include "src/core/lib/debug/stats.h"
#include "src/core/lib/gpr/spinlock.h"
#include "src/core/lib/gpr/tls.h"
#include "src/core/lib/gpr/useful.h"
#include "src/core/lib/gprpp/manual_constructor.h"
#include "src/core/lib/gprpp/ref_counted.h"
#include "src/core/lib/gprpp/sync.h"
#include "src/core/lib/iomgr/block_annotate.h"
#include "src/core/lib/iomgr/iomgr_internal.h"
#include "src/core/lib/iomgr/is_epollexclusive_available.h"
#include "src/core/lib/iomgr/lockfree_event.h"
#include "src/core/lib/iomgr/sys_epoll_wrapper.h"
#include "src/core/lib/iomgr/timer.h"
#include "src/core/lib/iomgr/wakeup_fd_posix.h"
#include "src/core/lib/profiling/timers.h"
// debug aid: create workers on the heap (allows asan to spot
// use-after-destruction)
//#define GRPC_EPOLLEX_CREATE_WORKERS_ON_HEAP 1
#define MAX_EPOLL_EVENTS 100
#define MAX_FDS_IN_CACHE 32
grpc_core::DebugOnlyTraceFlag grpc_trace_pollable_refcount(false,
"pollable_refcount");
/*******************************************************************************
* pollable Declarations
*/
typedef enum { PO_MULTI, PO_FD, PO_EMPTY } pollable_type;
typedef struct pollable pollable;
/// A pollable is something that can be polled: it has an epoll set to poll on,
/// and a wakeup fd for kicks
/// There are three broad types:
/// - PO_EMPTY - the empty pollable, used before file descriptors are added to
/// a pollset
/// - PO_FD - a pollable containing only one FD - used to optimize single-fd
/// pollsets (which are common with synchronous api usage)
/// - PO_MULTI - a pollable containing many fds
struct pollable {
pollable_type type; // immutable
grpc_core::RefCount refs;
int epfd;
grpc_wakeup_fd wakeup;
// The following are relevant only for type PO_FD
grpc_fd* owner_fd; // Set to the owner_fd if the type is PO_FD
gpr_mu owner_orphan_mu; // Synchronizes access to owner_orphaned field
bool owner_orphaned; // Is the owner fd orphaned
grpc_pollset_set* pollset_set;
pollable* next;
pollable* prev;
gpr_mu mu;
grpc_pollset_worker* root_worker;
int event_cursor;
int event_count;
struct epoll_event events[MAX_EPOLL_EVENTS];
};
static const char* pollable_type_string(pollable_type t) {
switch (t) {
case PO_MULTI:
return "pollset";
case PO_FD:
return "fd";
case PO_EMPTY:
return "empty";
}
return "<invalid>";
}
static std::string pollable_desc(pollable* p) {
return absl::StrFormat("type=%s epfd=%d wakeup=%d",
pollable_type_string(p->type), p->epfd,
p->wakeup.read_fd);
}
/// Shared empty pollable - used by pollset to poll on until the first fd is
/// added
static pollable* g_empty_pollable;
static grpc_error_handle pollable_create(pollable_type type, pollable** p);
static pollable* pollable_ref(pollable* p,
const grpc_core::DebugLocation& dbg_loc,
const char* reason) {
p->refs.Ref(dbg_loc, reason);
return p;
}
static void pollable_unref(pollable* p, const grpc_core::DebugLocation& dbg_loc,
const char* reason) {
if (p == nullptr) return;
if (GPR_UNLIKELY(p != nullptr && p->refs.Unref(dbg_loc, reason))) {
GRPC_FD_TRACE("pollable_unref: Closing epfd: %d", p->epfd);
close(p->epfd);
grpc_wakeup_fd_destroy(&p->wakeup);
gpr_mu_destroy(&p->owner_orphan_mu);
gpr_mu_destroy(&p->mu);
gpr_free(p);
}
}
#define POLLABLE_REF(p, r) pollable_ref((p), DEBUG_LOCATION, (r))
#define POLLABLE_UNREF(p, r) pollable_unref((p), DEBUG_LOCATION, (r))
/*******************************************************************************
* Fd Declarations
*/
struct grpc_fd {
grpc_fd(int fd, const char* name, bool track_err)
: fd(fd), track_err(track_err) {
gpr_mu_init(&orphan_mu);
gpr_mu_init(&pollable_mu);
read_closure.InitEvent();
write_closure.InitEvent();
error_closure.InitEvent();
std::string fd_name = absl::StrCat(name, " fd=", fd);
grpc_iomgr_register_object(&iomgr_object, fd_name.c_str());
#ifndef NDEBUG
if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_fd_refcount)) {
gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, this, fd_name.c_str());
}
#endif
}
// This is really the dtor, but the poller threads waking up from
// epoll_wait() may access the (read|write|error)_closure after destruction.
// Since the object will be added to the free pool, this behavior is
// not going to cause issues, except spurious events if the FD is reused
// while the race happens.
void destroy() {
grpc_iomgr_unregister_object(&iomgr_object);
POLLABLE_UNREF(pollable_obj, "fd_pollable");
// To clear out the allocations of pollset_fds, we need to swap its
// contents with a newly-constructed (and soon to be destructed) local
// variable of its same type. This is because InlinedVector::clear is _not_
// guaranteed to actually free up allocations and this is important since
// this object doesn't have a conventional destructor.
absl::InlinedVector<int, 1> pollset_fds_tmp;
pollset_fds_tmp.swap(pollset_fds);
gpr_mu_destroy(&pollable_mu);
gpr_mu_destroy(&orphan_mu);
read_closure.DestroyEvent();
write_closure.DestroyEvent();
error_closure.DestroyEvent();
invalidate();
}
#ifndef NDEBUG
/* Since an fd is never really destroyed (i.e gpr_free() is not called), it is
* hard-to-debug cases where fd fields are accessed even after calling
* fd_destroy(). The following invalidates fd fields to make catching such
* errors easier */
void invalidate() {
fd = -1;
gpr_atm_no_barrier_store(&refst, -1);
memset(&orphan_mu, -1, sizeof(orphan_mu));
memset(&pollable_mu, -1, sizeof(pollable_mu));
pollable_obj = nullptr;
on_done_closure = nullptr;
memset(&iomgr_object, -1, sizeof(iomgr_object));
track_err = false;
}
#else
void invalidate() {}
#endif
int fd;
// refst format:
// bit 0 : 1=Active / 0=Orphaned
// bits 1-n : refcount
// Ref/Unref by two to avoid altering the orphaned bit
gpr_atm refst = 1;
gpr_mu orphan_mu;
// Protects pollable_obj and pollset_fds.
gpr_mu pollable_mu;
absl::InlinedVector<int, 1> pollset_fds; // Used in PO_MULTI.
pollable* pollable_obj = nullptr; // Used in PO_FD.
grpc_core::LockfreeEvent read_closure;
grpc_core::LockfreeEvent write_closure;
grpc_core::LockfreeEvent error_closure;
struct grpc_fd* freelist_next = nullptr;
grpc_closure* on_done_closure = nullptr;
grpc_iomgr_object iomgr_object;
// Do we need to track EPOLLERR events separately?
bool track_err;
};
static void fd_global_init(void);
static void fd_global_shutdown(void);
/*******************************************************************************
* Pollset Declarations
*/
struct pwlink {
grpc_pollset_worker* next;
grpc_pollset_worker* prev;
};
typedef enum { PWLINK_POLLABLE = 0, PWLINK_POLLSET, PWLINK_COUNT } pwlinks;
struct grpc_pollset_worker {
bool kicked;
bool initialized_cv;
#ifndef NDEBUG
// debug aid: which thread started this worker
pid_t originator;
#endif
gpr_cv cv;
grpc_pollset* pollset;
pollable* pollable_obj;
pwlink links[PWLINK_COUNT];
};
struct grpc_pollset {
gpr_mu mu;
gpr_atm worker_count;
gpr_atm active_pollable_type;
pollable* active_pollable;
bool kicked_without_poller;
grpc_closure* shutdown_closure;
bool already_shutdown;
grpc_pollset_worker* root_worker;
int containing_pollset_set_count;
};
/*******************************************************************************
* Pollset-set Declarations
*/
struct grpc_pollset_set {
grpc_core::RefCount refs;
gpr_mu mu;
grpc_pollset_set* parent;
size_t pollset_count;
size_t pollset_capacity;
grpc_pollset** pollsets;
size_t fd_count;
size_t fd_capacity;
grpc_fd** fds;
};
/*******************************************************************************
* Common helpers
*/
static bool append_error(grpc_error_handle* composite, grpc_error_handle error,
const char* desc) {
if (error == GRPC_ERROR_NONE) return true;
if (*composite == GRPC_ERROR_NONE) {
*composite = GRPC_ERROR_CREATE_FROM_COPIED_STRING(desc);
}
*composite = grpc_error_add_child(*composite, error);
return false;
}
/*******************************************************************************
* Fd Definitions
*/
/* We need to keep a freelist not because of any concerns of malloc performance
* but instead so that implementations with multiple threads in (for example)
* epoll_wait deal with the race between pollset removal and incoming poll
* notifications.
*
* The problem is that the poller ultimately holds a reference to this
* object, so it is very difficult to know when is safe to free it, at least
* without some expensive synchronization.
*
* If we keep the object freelisted, in the worst case losing this race just
* becomes a spurious read notification on a reused fd.
*/
static grpc_fd* fd_freelist = nullptr;
static gpr_mu fd_freelist_mu;
#ifndef NDEBUG
#define REF_BY(fd, n, reason) ref_by(fd, n, reason, __FILE__, __LINE__)
#define UNREF_BY(fd, n, reason) unref_by(fd, n, reason, __FILE__, __LINE__)
static void ref_by(grpc_fd* fd, int n, const char* reason, const char* file,
int line) {
if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_fd_refcount)) {
gpr_log(GPR_DEBUG,
"FD %d %p ref %d %" PRIdPTR " -> %" PRIdPTR " [%s; %s:%d]",
fd->fd, fd, n, gpr_atm_no_barrier_load(&fd->refst),
gpr_atm_no_barrier_load(&fd->refst) + n, reason, file, line);
}
#else
#define REF_BY(fd, n, reason) \
do { \
ref_by(fd, n); \
(void)(reason); \
} while (0)
#define UNREF_BY(fd, n, reason) \
do { \
unref_by(fd, n); \
(void)(reason); \
} while (0)
static void ref_by(grpc_fd* fd, int n) {
#endif
GPR_ASSERT(gpr_atm_no_barrier_fetch_add(&fd->refst, n) > 0);
}
/* Uninitialize and add to the freelist */
static void fd_destroy(void* arg, grpc_error_handle /*error*/) {
grpc_fd* fd = static_cast<grpc_fd*>(arg);
fd->destroy();
/* Add the fd to the freelist */
gpr_mu_lock(&fd_freelist_mu);
fd->freelist_next = fd_freelist;
fd_freelist = fd;
gpr_mu_unlock(&fd_freelist_mu);
}
#ifndef NDEBUG
static void unref_by(grpc_fd* fd, int n, const char* reason, const char* file,
int line) {
if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_fd_refcount)) {
gpr_log(GPR_DEBUG,
"FD %d %p unref %d %" PRIdPTR " -> %" PRIdPTR " [%s; %s:%d]",
fd->fd, fd, n, gpr_atm_no_barrier_load(&fd->refst),
gpr_atm_no_barrier_load(&fd->refst) - n, reason, file, line);
}
#else
static void unref_by(grpc_fd* fd, int n) {
#endif
gpr_atm old = gpr_atm_full_fetch_add(&fd->refst, -n);
if (old == n) {
grpc_core::ExecCtx::Run(
DEBUG_LOCATION,
GRPC_CLOSURE_CREATE(fd_destroy, fd, grpc_schedule_on_exec_ctx),
GRPC_ERROR_NONE);
} else {
GPR_ASSERT(old > n);
}
}
static void fd_global_init(void) { gpr_mu_init(&fd_freelist_mu); }
static void fd_global_shutdown(void) {
// TODO(guantaol): We don't have a reasonable explanation about this
// lock()/unlock() pattern. It can be a valid barrier if there is at most one
// pending lock() at this point. Otherwise, there is still a possibility of
// use-after-free race. Need to reason about the code and/or clean it up.
gpr_mu_lock(&fd_freelist_mu);
gpr_mu_unlock(&fd_freelist_mu);
while (fd_freelist != nullptr) {
grpc_fd* fd = fd_freelist;
fd_freelist = fd_freelist->freelist_next;
gpr_free(fd);
}
gpr_mu_destroy(&fd_freelist_mu);
}
static grpc_fd* fd_create(int fd, const char* name, bool track_err) {
grpc_fd* new_fd = nullptr;
gpr_mu_lock(&fd_freelist_mu);
if (fd_freelist != nullptr) {
new_fd = fd_freelist;
fd_freelist = fd_freelist->freelist_next;
}
gpr_mu_unlock(&fd_freelist_mu);
if (new_fd == nullptr) {
new_fd = static_cast<grpc_fd*>(gpr_malloc(sizeof(grpc_fd)));
}
return new (new_fd) grpc_fd(fd, name, track_err);
}
static int fd_wrapped_fd(grpc_fd* fd) {
int ret_fd = fd->fd;
return (gpr_atm_acq_load(&fd->refst) & 1) ? ret_fd : -1;
}
static void fd_orphan(grpc_fd* fd, grpc_closure* on_done, int* release_fd,
const char* reason) {
bool is_fd_closed = false;
gpr_mu_lock(&fd->orphan_mu);
// Get the fd->pollable_obj and set the owner_orphaned on that pollable to
// true so that the pollable will no longer access its owner_fd field.
gpr_mu_lock(&fd->pollable_mu);
pollable* pollable_obj = fd->pollable_obj;
if (pollable_obj) {
gpr_mu_lock(&pollable_obj->owner_orphan_mu);
pollable_obj->owner_orphaned = true;
}
fd->on_done_closure = on_done;
/* If release_fd is not NULL, we should be relinquishing control of the file
descriptor fd->fd (but we still own the grpc_fd structure). */
if (release_fd != nullptr) {
// Remove the FD from all epolls sets, before releasing it.
// Otherwise, we will receive epoll events after we release the FD.
epoll_event ev_fd;
memset(&ev_fd, 0, sizeof(ev_fd));
if (pollable_obj != nullptr) { // For PO_FD.
epoll_ctl(pollable_obj->epfd, EPOLL_CTL_DEL, fd->fd, &ev_fd);
}
for (size_t i = 0; i < fd->pollset_fds.size(); ++i) { // For PO_MULTI.
const int epfd = fd->pollset_fds[i];
epoll_ctl(epfd, EPOLL_CTL_DEL, fd->fd, &ev_fd);
}
*release_fd = fd->fd;
} else {
close(fd->fd);
is_fd_closed = true;
}
// TODO(sreek): handle fd removal (where is_fd_closed=false)
if (!is_fd_closed) {
GRPC_FD_TRACE("epoll_fd %p (%d) was orphaned but not closed.", fd, fd->fd);
}
/* Remove the active status but keep referenced. We want this grpc_fd struct
to be alive (and not added to freelist) until the end of this function */
REF_BY(fd, 1, reason);
grpc_core::ExecCtx::Run(DEBUG_LOCATION, fd->on_done_closure, GRPC_ERROR_NONE);
if (pollable_obj) {
gpr_mu_unlock(&pollable_obj->owner_orphan_mu);
}
gpr_mu_unlock(&fd->pollable_mu);
gpr_mu_unlock(&fd->orphan_mu);
UNREF_BY(fd, 2, reason); /* Drop the reference */
}
static bool fd_is_shutdown(grpc_fd* fd) {
return fd->read_closure.IsShutdown();
}
/* Might be called multiple times */
static void fd_shutdown(grpc_fd* fd, grpc_error_handle why) {
if (fd->read_closure.SetShutdown(GRPC_ERROR_REF(why))) {
if (shutdown(fd->fd, SHUT_RDWR)) {
if (errno != ENOTCONN) {
gpr_log(GPR_ERROR, "Error shutting down fd %d. errno: %d",
grpc_fd_wrapped_fd(fd), errno);
}
}
fd->write_closure.SetShutdown(GRPC_ERROR_REF(why));
fd->error_closure.SetShutdown(GRPC_ERROR_REF(why));
}
GRPC_ERROR_UNREF(why);
}
static void fd_notify_on_read(grpc_fd* fd, grpc_closure* closure) {
fd->read_closure.NotifyOn(closure);
}
static void fd_notify_on_write(grpc_fd* fd, grpc_closure* closure) {
fd->write_closure.NotifyOn(closure);
}
static void fd_notify_on_error(grpc_fd* fd, grpc_closure* closure) {
fd->error_closure.NotifyOn(closure);
}
static bool fd_has_pollset(grpc_fd* fd, grpc_pollset* pollset) {
const int epfd = pollset->active_pollable->epfd;
grpc_core::MutexLockForGprMu lock(&fd->pollable_mu);
for (size_t i = 0; i < fd->pollset_fds.size(); ++i) {
if (fd->pollset_fds[i] == epfd) {
return true;
}
}
return false;
}
static void fd_add_pollset(grpc_fd* fd, grpc_pollset* pollset) {
const int epfd = pollset->active_pollable->epfd;
grpc_core::MutexLockForGprMu lock(&fd->pollable_mu);
fd->pollset_fds.push_back(epfd);
}
/*******************************************************************************
* Pollable Definitions
*/
static grpc_error_handle pollable_create(pollable_type type, pollable** p) {
*p = nullptr;
int epfd = epoll_create1(EPOLL_CLOEXEC);
if (epfd == -1) {
return GRPC_OS_ERROR(errno, "epoll_create1");
}
GRPC_FD_TRACE("Pollable_create: created epfd: %d (type: %d)", epfd, type);
*p = static_cast<pollable*>(gpr_malloc(sizeof(**p)));
grpc_error_handle err = grpc_wakeup_fd_init(&(*p)->wakeup);
if (err != GRPC_ERROR_NONE) {
GRPC_FD_TRACE(
"Pollable_create: closed epfd: %d (type: %d). wakeupfd_init error",
epfd, type);
close(epfd);
gpr_free(*p);
*p = nullptr;
return err;
}
struct epoll_event ev;
ev.events = static_cast<uint32_t>(EPOLLIN | EPOLLET);
ev.data.ptr =
reinterpret_cast<void*>(1 | reinterpret_cast<intptr_t>(&(*p)->wakeup));
if (epoll_ctl(epfd, EPOLL_CTL_ADD, (*p)->wakeup.read_fd, &ev) != 0) {
err = GRPC_OS_ERROR(errno, "epoll_ctl");
GRPC_FD_TRACE(
"Pollable_create: closed epfd: %d (type: %d). epoll_ctl error", epfd,
type);
close(epfd);
grpc_wakeup_fd_destroy(&(*p)->wakeup);
gpr_free(*p);
*p = nullptr;
return err;
}
(*p)->type = type;
new (&(*p)->refs) grpc_core::RefCount(
1, GRPC_TRACE_FLAG_ENABLED(grpc_trace_pollable_refcount)
? "pollable_refcount"
: nullptr);
gpr_mu_init(&(*p)->mu);
(*p)->epfd = epfd;
(*p)->owner_fd = nullptr;
gpr_mu_init(&(*p)->owner_orphan_mu);
(*p)->owner_orphaned = false;
(*p)->pollset_set = nullptr;
(*p)->next = (*p)->prev = *p;
(*p)->root_worker = nullptr;
(*p)->event_cursor = 0;
(*p)->event_count = 0;
return GRPC_ERROR_NONE;
}
static grpc_error_handle pollable_add_fd(pollable* p, grpc_fd* fd) {
grpc_error_handle error = GRPC_ERROR_NONE;
static const char* err_desc = "pollable_add_fd";
const int epfd = p->epfd;
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "add fd %p (%d) to pollable %p", fd, fd->fd, p);
}
struct epoll_event ev_fd;
ev_fd.events =
static_cast<uint32_t>(EPOLLET | EPOLLIN | EPOLLOUT | EPOLLEXCLUSIVE);
/* Use the second least significant bit of ev_fd.data.ptr to store track_err
* to avoid synchronization issues when accessing it after receiving an event.
* Accessing fd would be a data race there because the fd might have been
* returned to the free list at that point. */
ev_fd.data.ptr = reinterpret_cast<void*>(reinterpret_cast<intptr_t>(fd) |
(fd->track_err ? 2 : 0));
GRPC_STATS_INC_SYSCALL_EPOLL_CTL();
if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd->fd, &ev_fd) != 0) {
switch (errno) {
case EEXIST:
break;
default:
append_error(&error, GRPC_OS_ERROR(errno, "epoll_ctl"), err_desc);
}
}
return error;
}
/*******************************************************************************
* Pollset Definitions
*/
GPR_TLS_DECL(g_current_thread_pollset);
GPR_TLS_DECL(g_current_thread_worker);
/* Global state management */
static grpc_error_handle pollset_global_init(void) {
gpr_tls_init(&g_current_thread_pollset);
gpr_tls_init(&g_current_thread_worker);
return pollable_create(PO_EMPTY, &g_empty_pollable);
}
static void pollset_global_shutdown(void) {
POLLABLE_UNREF(g_empty_pollable, "g_empty_pollable");
gpr_tls_destroy(&g_current_thread_pollset);
gpr_tls_destroy(&g_current_thread_worker);
}
/* pollset->mu must be held while calling this function */
static void pollset_maybe_finish_shutdown(grpc_pollset* pollset) {
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO,
"PS:%p (pollable:%p) maybe_finish_shutdown sc=%p (target:!NULL) "
"rw=%p (target:NULL) cpsc=%d (target:0)",
pollset, pollset->active_pollable, pollset->shutdown_closure,
pollset->root_worker, pollset->containing_pollset_set_count);
}
if (pollset->shutdown_closure != nullptr && pollset->root_worker == nullptr &&
pollset->containing_pollset_set_count == 0) {
GPR_TIMER_MARK("pollset_finish_shutdown", 0);
grpc_core::ExecCtx::Run(DEBUG_LOCATION, pollset->shutdown_closure,
GRPC_ERROR_NONE);
pollset->shutdown_closure = nullptr;
pollset->already_shutdown = true;
}
}
/* pollset->mu must be held before calling this function,
* pollset->active_pollable->mu & specific_worker->pollable_obj->mu must not be
* held */
static grpc_error_handle kick_one_worker(grpc_pollset_worker* specific_worker) {
GPR_TIMER_SCOPE("kick_one_worker", 0);
pollable* p = specific_worker->pollable_obj;
grpc_core::MutexLockForGprMu lock(&p->mu);
GPR_ASSERT(specific_worker != nullptr);
if (specific_worker->kicked) {
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PS:%p kicked_specific_but_already_kicked", p);
}
GRPC_STATS_INC_POLLSET_KICKED_AGAIN();
return GRPC_ERROR_NONE;
}
if (gpr_tls_get(&g_current_thread_worker) ==
reinterpret_cast<intptr_t>(specific_worker)) {
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PS:%p kicked_specific_but_awake", p);
}
GRPC_STATS_INC_POLLSET_KICK_OWN_THREAD();
specific_worker->kicked = true;
return GRPC_ERROR_NONE;
}
if (specific_worker == p->root_worker) {
GRPC_STATS_INC_POLLSET_KICK_WAKEUP_FD();
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PS:%p kicked_specific_via_wakeup_fd", p);
}
specific_worker->kicked = true;
grpc_error_handle error = grpc_wakeup_fd_wakeup(&p->wakeup);
return error;
}
if (specific_worker->initialized_cv) {
GRPC_STATS_INC_POLLSET_KICK_WAKEUP_CV();
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PS:%p kicked_specific_via_cv", p);
}
specific_worker->kicked = true;
gpr_cv_signal(&specific_worker->cv);
return GRPC_ERROR_NONE;
}
// we can get here during end_worker after removing specific_worker from the
// pollable list but before removing it from the pollset list
return GRPC_ERROR_NONE;
}
static grpc_error_handle pollset_kick(grpc_pollset* pollset,
grpc_pollset_worker* specific_worker) {
GPR_TIMER_SCOPE("pollset_kick", 0);
GRPC_STATS_INC_POLLSET_KICK();
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO,
"PS:%p kick %p tls_pollset=%" PRIxPTR " tls_worker=%" PRIxPTR
" pollset.root_worker=%p",
pollset, specific_worker, gpr_tls_get(&g_current_thread_pollset),
gpr_tls_get(&g_current_thread_worker), pollset->root_worker);
}
if (specific_worker == nullptr) {
if (gpr_tls_get(&g_current_thread_pollset) !=
reinterpret_cast<intptr_t>(pollset)) {
if (pollset->root_worker == nullptr) {
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PS:%p kicked_any_without_poller", pollset);
}
GRPC_STATS_INC_POLLSET_KICKED_WITHOUT_POLLER();
pollset->kicked_without_poller = true;
return GRPC_ERROR_NONE;
} else {
// We've been asked to kick a poller, but we haven't been told which one
// ... any will do
// We look at the pollset worker list because:
// 1. the pollable list may include workers from other pollers, so we'd
// need to do an O(N) search
// 2. we'd additionally need to take the pollable lock, which we've so
// far avoided
// Now, we would prefer to wake a poller in cv_wait, and not in
// epoll_wait (since the latter would imply the need to do an additional
// wakeup)
// We know that if a worker is at the root of a pollable, it's (likely)
// also the root of a pollset, and we know that if a worker is NOT at
// the root of a pollset, it's (likely) not at the root of a pollable,
// so we take our chances and choose the SECOND worker enqueued against
// the pollset as a worker that's likely to be in cv_wait
return kick_one_worker(
pollset->root_worker->links[PWLINK_POLLSET].next);
}
} else {
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PS:%p kicked_any_but_awake", pollset);
}
GRPC_STATS_INC_POLLSET_KICK_OWN_THREAD();
return GRPC_ERROR_NONE;
}
} else {
return kick_one_worker(specific_worker);
}
}
static grpc_error_handle pollset_kick_all(grpc_pollset* pollset) {
GPR_TIMER_SCOPE("pollset_kick_all", 0);
grpc_error_handle error = GRPC_ERROR_NONE;
const char* err_desc = "pollset_kick_all";
grpc_pollset_worker* w = pollset->root_worker;
if (w != nullptr) {
do {
GRPC_STATS_INC_POLLSET_KICK();
append_error(&error, kick_one_worker(w), err_desc);
w = w->links[PWLINK_POLLSET].next;
} while (w != pollset->root_worker);
}
return error;
}
static void pollset_init(grpc_pollset* pollset, gpr_mu** mu) {
gpr_mu_init(&pollset->mu);
gpr_atm_no_barrier_store(&pollset->worker_count, 0);
gpr_atm_no_barrier_store(&pollset->active_pollable_type, PO_EMPTY);
pollset->active_pollable = POLLABLE_REF(g_empty_pollable, "pollset");
pollset->kicked_without_poller = false;
pollset->shutdown_closure = nullptr;
pollset->already_shutdown = false;
pollset->root_worker = nullptr;
pollset->containing_pollset_set_count = 0;
*mu = &pollset->mu;
}
static int poll_deadline_to_millis_timeout(grpc_millis millis) {
if (millis == GRPC_MILLIS_INF_FUTURE) return -1;
grpc_millis delta = millis - grpc_core::ExecCtx::Get()->Now();
if (delta > INT_MAX) {
return INT_MAX;
} else if (delta < 0) {
return 0;
} else {
return static_cast<int>(delta);
}
}
static void fd_become_readable(grpc_fd* fd) { fd->read_closure.SetReady(); }
static void fd_become_writable(grpc_fd* fd) { fd->write_closure.SetReady(); }
static void fd_has_errors(grpc_fd* fd) { fd->error_closure.SetReady(); }
/* Get the pollable_obj attached to this fd. If none is attached, create a new
* pollable object (of type PO_FD), attach it to the fd and return it
*
* Note that if a pollable object is already attached to the fd, it may be of
* either PO_FD or PO_MULTI type */
static grpc_error_handle get_fd_pollable(grpc_fd* fd, pollable** p) {
gpr_mu_lock(&fd->pollable_mu);
grpc_error_handle error = GRPC_ERROR_NONE;
static const char* err_desc = "get_fd_pollable";
if (fd->pollable_obj == nullptr) {
if (append_error(&error, pollable_create(PO_FD, &fd->pollable_obj),
err_desc)) {
fd->pollable_obj->owner_fd = fd;
if (!append_error(&error, pollable_add_fd(fd->pollable_obj, fd),
err_desc)) {
POLLABLE_UNREF(fd->pollable_obj, "fd_pollable");
fd->pollable_obj = nullptr;
}
}
}
if (error == GRPC_ERROR_NONE) {
GPR_ASSERT(fd->pollable_obj != nullptr);
*p = POLLABLE_REF(fd->pollable_obj, "pollset");
} else {
GPR_ASSERT(fd->pollable_obj == nullptr);
*p = nullptr;
}
gpr_mu_unlock(&fd->pollable_mu);
return error;
}
/* pollset->po.mu lock must be held by the caller before calling this */
static void pollset_shutdown(grpc_pollset* pollset, grpc_closure* closure) {
GPR_TIMER_SCOPE("pollset_shutdown", 0);
GPR_ASSERT(pollset->shutdown_closure == nullptr);
pollset->shutdown_closure = closure;
GRPC_LOG_IF_ERROR("pollset_shutdown", pollset_kick_all(pollset));
pollset_maybe_finish_shutdown(pollset);
}
static grpc_error_handle pollable_process_events(grpc_pollset* pollset,
pollable* pollable_obj,
bool drain) {
GPR_TIMER_SCOPE("pollable_process_events", 0);
static const char* err_desc = "pollset_process_events";
// Use a simple heuristic to determine how many fd events to process
// per loop iteration. (events/workers)
int handle_count = 1;
int worker_count = gpr_atm_no_barrier_load(&pollset->worker_count);
GPR_ASSERT(worker_count > 0);
handle_count =
(pollable_obj->event_count - pollable_obj->event_cursor) / worker_count;
if (handle_count == 0) {
handle_count = 1;
}
grpc_error_handle error = GRPC_ERROR_NONE;
for (int i = 0; (drain || i < handle_count) &&
pollable_obj->event_cursor != pollable_obj->event_count;
i++) {
int n = pollable_obj->event_cursor++;
struct epoll_event* ev = &pollable_obj->events[n];
void* data_ptr = ev->data.ptr;
if (1 & reinterpret_cast<intptr_t>(data_ptr)) {
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PS:%p got pollset_wakeup %p", pollset, data_ptr);
}
append_error(
&error,
grpc_wakeup_fd_consume_wakeup(reinterpret_cast<grpc_wakeup_fd*>(
~static_cast<intptr_t>(1) &
reinterpret_cast<intptr_t>(data_ptr))),
err_desc);
} else {
grpc_fd* fd =
reinterpret_cast<grpc_fd*>(reinterpret_cast<intptr_t>(data_ptr) & ~2);
bool track_err = reinterpret_cast<intptr_t>(data_ptr) & 2;
bool cancel = (ev->events & EPOLLHUP) != 0;
bool error = (ev->events & EPOLLERR) != 0;
bool read_ev = (ev->events & (EPOLLIN | EPOLLPRI)) != 0;
bool write_ev = (ev->events & EPOLLOUT) != 0;
bool err_fallback = error && !track_err;
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO,
"PS:%p got fd %p: cancel=%d read=%d "
"write=%d",
pollset, fd, cancel, read_ev, write_ev);
}
if (error && !err_fallback) {
fd_has_errors(fd);
}
if (read_ev || cancel || err_fallback) {
fd_become_readable(fd);
}
if (write_ev || cancel || err_fallback) {
fd_become_writable(fd);
}
}
}
return error;
}
/* pollset_shutdown is guaranteed to be called before pollset_destroy. */
static void pollset_destroy(grpc_pollset* pollset) {
POLLABLE_UNREF(pollset->active_pollable, "pollset");
pollset->active_pollable = nullptr;
gpr_mu_destroy(&pollset->mu);
}
static grpc_error_handle pollable_epoll(pollable* p, grpc_millis deadline) {
GPR_TIMER_SCOPE("pollable_epoll", 0);
int timeout = poll_deadline_to_millis_timeout(deadline);
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "POLLABLE:%p[%s] poll for %dms", p,
pollable_desc(p).c_str(), timeout);
}
if (timeout != 0) {
GRPC_SCHEDULING_START_BLOCKING_REGION;
}
int r;
do {
GRPC_STATS_INC_SYSCALL_POLL();
r = epoll_wait(p->epfd, p->events, MAX_EPOLL_EVENTS, timeout);
} while (r < 0 && errno == EINTR);
if (timeout != 0) {
GRPC_SCHEDULING_END_BLOCKING_REGION;
}
if (r < 0) return GRPC_OS_ERROR(errno, "epoll_wait");
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "POLLABLE:%p got %d events", p, r);
}
p->event_cursor = 0;
p->event_count = r;
return GRPC_ERROR_NONE;
}
/* Return true if first in list */
static bool worker_insert(grpc_pollset_worker** root_worker,
grpc_pollset_worker* worker, pwlinks link) {
if (*root_worker == nullptr) {
*root_worker = worker;
worker->links[link].next = worker->links[link].prev = worker;
return true;
} else {
worker->links[link].next = *root_worker;
worker->links[link].prev = worker->links[link].next->links[link].prev;
worker->links[link].next->links[link].prev = worker;
worker->links[link].prev->links[link].next = worker;
return false;
}
}
/* returns the new root IFF the root changed */
typedef enum { WRR_NEW_ROOT, WRR_EMPTIED, WRR_REMOVED } worker_remove_result;
static worker_remove_result worker_remove(grpc_pollset_worker** root_worker,
grpc_pollset_worker* worker,
pwlinks link) {
if (worker == *root_worker) {
if (worker == worker->links[link].next) {
*root_worker = nullptr;
return WRR_EMPTIED;
} else {
*root_worker = worker->links[link].next;
worker->links[link].prev->links[link].next = worker->links[link].next;
worker->links[link].next->links[link].prev = worker->links[link].prev;
return WRR_NEW_ROOT;
}
} else {
worker->links[link].prev->links[link].next = worker->links[link].next;
worker->links[link].next->links[link].prev = worker->links[link].prev;
return WRR_REMOVED;
}
}
/* Return true if this thread should poll */
static bool begin_worker(grpc_pollset* pollset, grpc_pollset_worker* worker,
grpc_pollset_worker** worker_hdl,
grpc_millis deadline) {
GPR_TIMER_SCOPE("begin_worker", 0);
bool do_poll =
(pollset->shutdown_closure == nullptr && !pollset->already_shutdown);
gpr_atm_no_barrier_fetch_add(&pollset->worker_count, 1);
if (worker_hdl != nullptr) *worker_hdl = worker;
worker->initialized_cv = false;
worker->kicked = false;
worker->pollset = pollset;
worker->pollable_obj =
POLLABLE_REF(pollset->active_pollable, "pollset_worker");
worker_insert(&pollset->root_worker, worker, PWLINK_POLLSET);
gpr_mu_lock(&worker->pollable_obj->mu);
if (!worker_insert(&worker->pollable_obj->root_worker, worker,
PWLINK_POLLABLE)) {
worker->initialized_cv = true;
gpr_cv_init(&worker->cv);
gpr_mu_unlock(&pollset->mu);
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace) &&
worker->pollable_obj->root_worker != worker) {
gpr_log(GPR_INFO, "PS:%p wait %p w=%p for %dms", pollset,
worker->pollable_obj, worker,
poll_deadline_to_millis_timeout(deadline));
}
while (do_poll && worker->pollable_obj->root_worker != worker) {
if (gpr_cv_wait(&worker->cv, &worker->pollable_obj->mu,
grpc_millis_to_timespec(deadline, GPR_CLOCK_REALTIME))) {
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PS:%p timeout_wait %p w=%p", pollset,
worker->pollable_obj, worker);
}
do_poll = false;
} else if (worker->kicked) {
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PS:%p wakeup %p w=%p", pollset,
worker->pollable_obj, worker);
}
do_poll = false;
} else if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace) &&
worker->pollable_obj->root_worker != worker) {
gpr_log(GPR_INFO, "PS:%p spurious_wakeup %p w=%p", pollset,
worker->pollable_obj, worker);
}
}
grpc_core::ExecCtx::Get()->InvalidateNow();
} else {
gpr_mu_unlock(&pollset->mu);
}
gpr_mu_unlock(&worker->pollable_obj->mu);
return do_poll;
}
static void end_worker(grpc_pollset* pollset, grpc_pollset_worker* worker,
grpc_pollset_worker** /*worker_hdl*/) {
GPR_TIMER_SCOPE("end_worker", 0);
gpr_mu_lock(&pollset->mu);
gpr_mu_lock(&worker->pollable_obj->mu);
switch (worker_remove(&worker->pollable_obj->root_worker, worker,
PWLINK_POLLABLE)) {
case WRR_NEW_ROOT: {
// wakeup new poller
grpc_pollset_worker* new_root = worker->pollable_obj->root_worker;
GPR_ASSERT(new_root->initialized_cv);
gpr_cv_signal(&new_root->cv);
break;
}
case WRR_EMPTIED:
if (pollset->active_pollable != worker->pollable_obj) {
// pollable no longer being polled: flush events
pollable_process_events(pollset, worker->pollable_obj, true);
}
break;
case WRR_REMOVED:
break;
}
gpr_mu_unlock(&worker->pollable_obj->mu);
POLLABLE_UNREF(worker->pollable_obj, "pollset_worker");
if (worker_remove(&pollset->root_worker, worker, PWLINK_POLLSET) ==
WRR_EMPTIED) {
pollset_maybe_finish_shutdown(pollset);
}
if (worker->initialized_cv) {
gpr_cv_destroy(&worker->cv);
}
gpr_atm_no_barrier_fetch_add(&pollset->worker_count, -1);
}
#ifndef NDEBUG
static long sys_gettid(void) { return syscall(__NR_gettid); }
#endif
/* pollset->mu lock must be held by the caller before calling this.
The function pollset_work() may temporarily release the lock (pollset->po.mu)
during the course of its execution but it will always re-acquire the lock and
ensure that it is held by the time the function returns */
static grpc_error_handle pollset_work(grpc_pollset* pollset,
grpc_pollset_worker** worker_hdl,
grpc_millis deadline) {
GPR_TIMER_SCOPE("pollset_work", 0);
#ifdef GRPC_EPOLLEX_CREATE_WORKERS_ON_HEAP
grpc_pollset_worker* worker =
(grpc_pollset_worker*)gpr_malloc(sizeof(*worker));
#define WORKER_PTR (worker)
#else
grpc_pollset_worker worker;
#define WORKER_PTR (&worker)
#endif
#ifndef NDEBUG
WORKER_PTR->originator = sys_gettid();
#endif
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO,
"PS:%p work hdl=%p worker=%p now=%" PRId64 " deadline=%" PRId64
" kwp=%d pollable=%p",
pollset, worker_hdl, WORKER_PTR, grpc_core::ExecCtx::Get()->Now(),
deadline, pollset->kicked_without_poller, pollset->active_pollable);
}
static const char* err_desc = "pollset_work";
grpc_error_handle error = GRPC_ERROR_NONE;
if (pollset->kicked_without_poller) {
pollset->kicked_without_poller = false;
} else {
if (begin_worker(pollset, WORKER_PTR, worker_hdl, deadline)) {
gpr_tls_set(&g_current_thread_pollset, (intptr_t)pollset);
gpr_tls_set(&g_current_thread_worker, (intptr_t)WORKER_PTR);
if (WORKER_PTR->pollable_obj->event_cursor ==
WORKER_PTR->pollable_obj->event_count) {
append_error(&error, pollable_epoll(WORKER_PTR->pollable_obj, deadline),
err_desc);
}
append_error(
&error,
pollable_process_events(pollset, WORKER_PTR->pollable_obj, false),
err_desc);
grpc_core::ExecCtx::Get()->Flush();
gpr_tls_set(&g_current_thread_pollset, 0);
gpr_tls_set(&g_current_thread_worker, 0);
}
end_worker(pollset, WORKER_PTR, worker_hdl);
}
#ifdef GRPC_EPOLLEX_CREATE_WORKERS_ON_HEAP
gpr_free(worker);
#endif
#undef WORKER_PTR
return error;
}
static grpc_error_handle pollset_transition_pollable_from_empty_to_fd_locked(
grpc_pollset* pollset, grpc_fd* fd) {
static const char* err_desc = "pollset_transition_pollable_from_empty_to_fd";
grpc_error_handle error = GRPC_ERROR_NONE;
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO,
"PS:%p add fd %p (%d); transition pollable from empty to fd",
pollset, fd, fd->fd);
}
append_error(&error, pollset_kick_all(pollset), err_desc);
POLLABLE_UNREF(pollset->active_pollable, "pollset");
append_error(&error, get_fd_pollable(fd, &pollset->active_pollable),
err_desc);
return error;
}
static grpc_error_handle pollset_transition_pollable_from_fd_to_multi_locked(
grpc_pollset* pollset, grpc_fd* and_add_fd) {
static const char* err_desc = "pollset_transition_pollable_from_fd_to_multi";
grpc_error_handle error = GRPC_ERROR_NONE;
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(
GPR_INFO,
"PS:%p add fd %p (%d); transition pollable from fd %p to multipoller",
pollset, and_add_fd, and_add_fd ? and_add_fd->fd : -1,
pollset->active_pollable->owner_fd);
}
append_error(&error, pollset_kick_all(pollset), err_desc);
grpc_fd* initial_fd = pollset->active_pollable->owner_fd;
POLLABLE_UNREF(pollset->active_pollable, "pollset");
pollset->active_pollable = nullptr;
if (append_error(&error, pollable_create(PO_MULTI, &pollset->active_pollable),
err_desc)) {
append_error(&error, pollable_add_fd(pollset->active_pollable, initial_fd),
err_desc);
if (and_add_fd != nullptr) {
append_error(&error,
pollable_add_fd(pollset->active_pollable, and_add_fd),
err_desc);
}
}
return error;
}
/* expects pollsets locked, flag whether fd is locked or not */
static grpc_error_handle pollset_add_fd_locked(grpc_pollset* pollset,
grpc_fd* fd) {
grpc_error_handle error = GRPC_ERROR_NONE;
pollable* po_at_start =
POLLABLE_REF(pollset->active_pollable, "pollset_add_fd");
switch (pollset->active_pollable->type) {
case PO_EMPTY:
/* empty pollable --> single fd pollable */
error = pollset_transition_pollable_from_empty_to_fd_locked(pollset, fd);
break;
case PO_FD:
gpr_mu_lock(&po_at_start->owner_orphan_mu);
if (po_at_start->owner_orphaned) {
error =
pollset_transition_pollable_from_empty_to_fd_locked(pollset, fd);
} else {
/* fd --> multipoller */
error =
pollset_transition_pollable_from_fd_to_multi_locked(pollset, fd);
}
gpr_mu_unlock(&po_at_start->owner_orphan_mu);
break;
case PO_MULTI:
error = pollable_add_fd(pollset->active_pollable, fd);
break;
}
if (error != GRPC_ERROR_NONE) {
POLLABLE_UNREF(pollset->active_pollable, "pollset");
pollset->active_pollable = po_at_start;
} else {
gpr_atm_rel_store(&pollset->active_pollable_type,
pollset->active_pollable->type);
POLLABLE_UNREF(po_at_start, "pollset_add_fd");
}
return error;
}
static grpc_error_handle pollset_as_multipollable_locked(
grpc_pollset* pollset, pollable** pollable_obj) {
grpc_error_handle error = GRPC_ERROR_NONE;
pollable* po_at_start =
POLLABLE_REF(pollset->active_pollable, "pollset_as_multipollable");
switch (pollset->active_pollable->type) {
case PO_EMPTY:
POLLABLE_UNREF(pollset->active_pollable, "pollset");
error = pollable_create(PO_MULTI, &pollset->active_pollable);
/* Any workers currently polling on this pollset must now be woked up so
* that they can pick up the new active_pollable */
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO,
"PS:%p active pollable transition from empty to multi",
pollset);
}
static const char* err_desc =
"pollset_as_multipollable_locked: empty -> multi";
append_error(&error, pollset_kick_all(pollset), err_desc);
break;
case PO_FD:
gpr_mu_lock(&po_at_start->owner_orphan_mu);
if (po_at_start->owner_orphaned) {
// Unlock before Unref'ing the pollable
gpr_mu_unlock(&po_at_start->owner_orphan_mu);
POLLABLE_UNREF(pollset->active_pollable, "pollset");
error = pollable_create(PO_MULTI, &pollset->active_pollable);
} else {
error = pollset_transition_pollable_from_fd_to_multi_locked(pollset,
nullptr);
gpr_mu_unlock(&po_at_start->owner_orphan_mu);
}
break;
case PO_MULTI:
break;
}
if (error != GRPC_ERROR_NONE) {
POLLABLE_UNREF(pollset->active_pollable, "pollset");
pollset->active_pollable = po_at_start;
*pollable_obj = nullptr;
} else {
gpr_atm_rel_store(&pollset->active_pollable_type,
pollset->active_pollable->type);
*pollable_obj = POLLABLE_REF(pollset->active_pollable, "pollset_set");
POLLABLE_UNREF(po_at_start, "pollset_as_multipollable");
}
return error;
}
static void pollset_add_fd(grpc_pollset* pollset, grpc_fd* fd) {
GPR_TIMER_SCOPE("pollset_add_fd", 0);
// We never transition from PO_MULTI to other modes (i.e., PO_FD or PO_EMPTY)
// and, thus, it is safe to simply store and check whether the FD has already
// been added to the active pollable previously.
if (gpr_atm_acq_load(&pollset->active_pollable_type) == PO_MULTI &&
fd_has_pollset(fd, pollset)) {
return;
}
grpc_core::MutexLockForGprMu lock(&pollset->mu);
grpc_error_handle error = pollset_add_fd_locked(pollset, fd);
// If we are in PO_MULTI mode, we should update the pollsets of the FD.
if (gpr_atm_no_barrier_load(&pollset->active_pollable_type) == PO_MULTI) {
fd_add_pollset(fd, pollset);
}
GRPC_LOG_IF_ERROR("pollset_add_fd", error);
}
/*******************************************************************************
* Pollset-set Definitions
*/
static grpc_pollset_set* pss_lock_adam(grpc_pollset_set* pss) {
gpr_mu_lock(&pss->mu);
while (pss->parent != nullptr) {
gpr_mu_unlock(&pss->mu);
pss = pss->parent;
gpr_mu_lock(&pss->mu);
}
return pss;
}
static grpc_pollset_set* pollset_set_create(void) {
grpc_pollset_set* pss =
static_cast<grpc_pollset_set*>(gpr_zalloc(sizeof(*pss)));
gpr_mu_init(&pss->mu);
new (&pss->refs) grpc_core::RefCount();
return pss;
}
static void pollset_set_unref(grpc_pollset_set* pss) {
if (pss == nullptr) return;
if (GPR_LIKELY(!pss->refs.Unref())) return;
pollset_set_unref(pss->parent);
gpr_mu_destroy(&pss->mu);
for (size_t i = 0; i < pss->pollset_count; i++) {
gpr_mu_lock(&pss->pollsets[i]->mu);
if (0 == --pss->pollsets[i]->containing_pollset_set_count) {
pollset_maybe_finish_shutdown(pss->pollsets[i]);
}
gpr_mu_unlock(&pss->pollsets[i]->mu);
}
for (size_t i = 0; i < pss->fd_count; i++) {
UNREF_BY(pss->fds[i], 2, "pollset_set");
}
gpr_free(pss->pollsets);
gpr_free(pss->fds);
gpr_free(pss);
}
static void pollset_set_add_fd(grpc_pollset_set* pss, grpc_fd* fd) {
GPR_TIMER_SCOPE("pollset_set_add_fd", 0);
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PSS:%p: add fd %p (%d)", pss, fd, fd->fd);
}
grpc_error_handle error = GRPC_ERROR_NONE;
static const char* err_desc = "pollset_set_add_fd";
pss = pss_lock_adam(pss);
for (size_t i = 0; i < pss->pollset_count; i++) {
append_error(&error, pollable_add_fd(pss->pollsets[i]->active_pollable, fd),
err_desc);
}
if (pss->fd_count == pss->fd_capacity) {
pss->fd_capacity = GPR_MAX(pss->fd_capacity * 2, 8);
pss->fds = static_cast<grpc_fd**>(
gpr_realloc(pss->fds, pss->fd_capacity * sizeof(*pss->fds)));
}
REF_BY(fd, 2, "pollset_set");
pss->fds[pss->fd_count++] = fd;
gpr_mu_unlock(&pss->mu);
GRPC_LOG_IF_ERROR(err_desc, error);
}
static void pollset_set_del_fd(grpc_pollset_set* pss, grpc_fd* fd) {
GPR_TIMER_SCOPE("pollset_set_del_fd", 0);
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PSS:%p: del fd %p", pss, fd);
}
pss = pss_lock_adam(pss);
size_t i;
for (i = 0; i < pss->fd_count; i++) {
if (pss->fds[i] == fd) {
UNREF_BY(fd, 2, "pollset_set");
break;
}
}
GPR_ASSERT(i != pss->fd_count);
for (; i < pss->fd_count - 1; i++) {
pss->fds[i] = pss->fds[i + 1];
}
pss->fd_count--;
gpr_mu_unlock(&pss->mu);
}
static void pollset_set_del_pollset(grpc_pollset_set* pss, grpc_pollset* ps) {
GPR_TIMER_SCOPE("pollset_set_del_pollset", 0);
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PSS:%p: del pollset %p", pss, ps);
}
pss = pss_lock_adam(pss);
size_t i;
for (i = 0; i < pss->pollset_count; i++) {
if (pss->pollsets[i] == ps) {
break;
}
}
GPR_ASSERT(i != pss->pollset_count);
for (; i < pss->pollset_count - 1; i++) {
pss->pollsets[i] = pss->pollsets[i + 1];
}
pss->pollset_count--;
gpr_mu_unlock(&pss->mu);
gpr_mu_lock(&ps->mu);
if (0 == --ps->containing_pollset_set_count) {
pollset_maybe_finish_shutdown(ps);
}
gpr_mu_unlock(&ps->mu);
}
// add all fds to pollables, and output a new array of unorphaned out_fds
// assumes pollsets are multipollable
static grpc_error_handle add_fds_to_pollsets(grpc_fd** fds, size_t fd_count,
grpc_pollset** pollsets,
size_t pollset_count,
const char* err_desc,
grpc_fd** out_fds,
size_t* out_fd_count) {
GPR_TIMER_SCOPE("add_fds_to_pollsets", 0);
grpc_error_handle error = GRPC_ERROR_NONE;
for (size_t i = 0; i < fd_count; i++) {
gpr_mu_lock(&fds[i]->orphan_mu);
if ((gpr_atm_no_barrier_load(&fds[i]->refst) & 1) == 0) {
gpr_mu_unlock(&fds[i]->orphan_mu);
UNREF_BY(fds[i], 2, "pollset_set");
} else {
for (size_t j = 0; j < pollset_count; j++) {
append_error(&error,
pollable_add_fd(pollsets[j]->active_pollable, fds[i]),
err_desc);
}
gpr_mu_unlock(&fds[i]->orphan_mu);
out_fds[(*out_fd_count)++] = fds[i];
}
}
return error;
}
static void pollset_set_add_pollset(grpc_pollset_set* pss, grpc_pollset* ps) {
GPR_TIMER_SCOPE("pollset_set_add_pollset", 0);
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PSS:%p: add pollset %p", pss, ps);
}
grpc_error_handle error = GRPC_ERROR_NONE;
static const char* err_desc = "pollset_set_add_pollset";
pollable* pollable_obj = nullptr;
gpr_mu_lock(&ps->mu);
if (!GRPC_LOG_IF_ERROR(err_desc,
pollset_as_multipollable_locked(ps, &pollable_obj))) {
GPR_ASSERT(pollable_obj == nullptr);
gpr_mu_unlock(&ps->mu);
return;
}
ps->containing_pollset_set_count++;
gpr_mu_unlock(&ps->mu);
pss = pss_lock_adam(pss);
size_t initial_fd_count = pss->fd_count;
pss->fd_count = 0;
append_error(&error,
add_fds_to_pollsets(pss->fds, initial_fd_count, &ps, 1, err_desc,
pss->fds, &pss->fd_count),
err_desc);
if (pss->pollset_count == pss->pollset_capacity) {
pss->pollset_capacity = GPR_MAX(pss->pollset_capacity * 2, 8);
pss->pollsets = static_cast<grpc_pollset**>(gpr_realloc(
pss->pollsets, pss->pollset_capacity * sizeof(*pss->pollsets)));
}
pss->pollsets[pss->pollset_count++] = ps;
gpr_mu_unlock(&pss->mu);
POLLABLE_UNREF(pollable_obj, "pollset_set");
GRPC_LOG_IF_ERROR(err_desc, error);
}
static void pollset_set_add_pollset_set(grpc_pollset_set* a,
grpc_pollset_set* b) {
GPR_TIMER_SCOPE("pollset_set_add_pollset_set", 0);
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PSS: merge (%p, %p)", a, b);
}
grpc_error_handle error = GRPC_ERROR_NONE;
static const char* err_desc = "pollset_set_add_fd";
for (;;) {
if (a == b) {
// pollset ancestors are the same: nothing to do
return;
}
if (a > b) {
GPR_SWAP(grpc_pollset_set*, a, b);
}
gpr_mu* a_mu = &a->mu;
gpr_mu* b_mu = &b->mu;
gpr_mu_lock(a_mu);
gpr_mu_lock(b_mu);
if (a->parent != nullptr) {
a = a->parent;
} else if (b->parent != nullptr) {
b = b->parent;
} else {
break; // exit loop, both pollsets locked
}
gpr_mu_unlock(a_mu);
gpr_mu_unlock(b_mu);
}
// try to do the least copying possible
// TODO(sreek): there's probably a better heuristic here
const size_t a_size = a->fd_count + a->pollset_count;
const size_t b_size = b->fd_count + b->pollset_count;
if (b_size > a_size) {
GPR_SWAP(grpc_pollset_set*, a, b);
}
if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
gpr_log(GPR_INFO, "PSS: parent %p to %p", b, a);
}
a->refs.Ref();
b->parent = a;
if (a->fd_capacity < a->fd_count + b->fd_count) {
a->fd_capacity = GPR_MAX(2 * a->fd_capacity, a->fd_count + b->fd_count);
a->fds = static_cast<grpc_fd**>(
gpr_realloc(a->fds, a->fd_capacity * sizeof(*a->fds)));
}
size_t initial_a_fd_count = a->fd_count;
a->fd_count = 0;
append_error(
&error,
add_fds_to_pollsets(a->fds, initial_a_fd_count, b->pollsets,
b->pollset_count, "merge_a2b", a->fds, &a->fd_count),
err_desc);
append_error(
&error,
add_fds_to_pollsets(b->fds, b->fd_count, a->pollsets, a->pollset_count,
"merge_b2a", a->fds, &a->fd_count),
err_desc);
if (a->pollset_capacity < a->pollset_count + b->pollset_count) {
a->pollset_capacity =
GPR_MAX(2 * a->pollset_capacity, a->pollset_count + b->pollset_count);
a->pollsets = static_cast<grpc_pollset**>(
gpr_realloc(a->pollsets, a->pollset_capacity * sizeof(*a->pollsets)));
}
if (b->pollset_count > 0) {
memcpy(a->pollsets + a->pollset_count, b->pollsets,
b->pollset_count * sizeof(*b->pollsets));
}
a->pollset_count += b->pollset_count;
gpr_free(b->fds);
gpr_free(b->pollsets);
b->fds = nullptr;
b->pollsets = nullptr;
b->fd_count = b->fd_capacity = b->pollset_count = b->pollset_capacity = 0;
gpr_mu_unlock(&a->mu);
gpr_mu_unlock(&b->mu);
}
static void pollset_set_del_pollset_set(grpc_pollset_set* /*bag*/,
grpc_pollset_set* /*item*/) {}
/*******************************************************************************
* Event engine binding
*/
static bool is_any_background_poller_thread(void) { return false; }
static void shutdown_background_closure(void) {}
static bool add_closure_to_background_poller(grpc_closure* /*closure*/,
grpc_error_handle /*error*/) {
return false;
}
static void shutdown_engine(void) {
fd_global_shutdown();
pollset_global_shutdown();
}
static const grpc_event_engine_vtable vtable = {
sizeof(grpc_pollset),
true,
false,
fd_create,
fd_wrapped_fd,
fd_orphan,
fd_shutdown,
fd_notify_on_read,
fd_notify_on_write,
fd_notify_on_error,
fd_become_readable,
fd_become_writable,
fd_has_errors,
fd_is_shutdown,
pollset_init,
pollset_shutdown,
pollset_destroy,
pollset_work,
pollset_kick,
pollset_add_fd,
pollset_set_create,
pollset_set_unref, // destroy ==> unref 1 public ref
pollset_set_add_pollset,
pollset_set_del_pollset,
pollset_set_add_pollset_set,
pollset_set_del_pollset_set,
pollset_set_add_fd,
pollset_set_del_fd,
is_any_background_poller_thread,
shutdown_background_closure,
shutdown_engine,
add_closure_to_background_poller,
};
const grpc_event_engine_vtable* grpc_init_epollex_linux(
bool /*explicitly_requested*/) {
if (!grpc_has_wakeup_fd()) {
gpr_log(GPR_ERROR, "Skipping epollex because of no wakeup fd.");
return nullptr;
}
if (!grpc_is_epollexclusive_available()) {
gpr_log(GPR_INFO, "Skipping epollex because it is not supported.");
return nullptr;
}
fd_global_init();
if (!GRPC_LOG_IF_ERROR("pollset_global_init", pollset_global_init())) {
pollset_global_shutdown();
fd_global_shutdown();
return nullptr;
}
return &vtable;
}
#else /* defined(GRPC_LINUX_EPOLL_CREATE1) */
#if defined(GRPC_POSIX_SOCKET_EV_EPOLLEX)
#include "src/core/lib/iomgr/ev_epollex_linux.h"
/* If GRPC_LINUX_EPOLL_CREATE1 is not defined, it means
epoll_create1 is not available. Return NULL */
const grpc_event_engine_vtable* grpc_init_epollex_linux(
bool /*explicitly_requested*/) {
return nullptr;
}
#endif /* defined(GRPC_POSIX_SOCKET_EV_EPOLLEX) */
#endif /* !defined(GRPC_LINUX_EPOLL_CREATE1) */