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android / platform / dalvik-snapshot / refs/heads/gingerbread / . / vm / alloc / Copying.c
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/*
* Copyright (C) 2009 The Android Open Source Project
*
* 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 <errno.h>
#include <limits.h>
#include <sys/mman.h>
#include "Dalvik.h"
#include "alloc/Heap.h"
#include "alloc/HeapBitmap.h"
#include "alloc/HeapInternal.h"
#include "alloc/HeapSource.h"
#include "alloc/Verify.h"
#include "alloc/clz.h"
/*
* A "mostly copying", generational, garbage collector.
*
* TODO: we allocate our own contiguous tract of page frames to back
* object allocations. To cooperate with other heaps active in the
* virtual machine we need to move the responsibility of allocating
* pages someplace outside of this code.
*
* The other major data structures that maintain the state of the heap
* are the block space table and the block queue.
*
* The block space table records the state of a block. We must track
* whether a block is:
*
* - Free or allocated in some space.
*
* - If the block holds part of a large object allocation, whether the
* block is the initial or a continued block of the allocation.
*
* - Whether the block is pinned, that is to say whether at least one
* object in the block must remain stationary. Only needed during a
* GC.
*
* - Which space the object belongs to. At present this means
* from-space or to-space.
*
* The block queue is used during garbage collection. Unlike Cheney's
* algorithm, from-space and to-space are not contiguous. Therefore,
* one cannot maintain the state of the copy with just two pointers.
* The block queue exists to thread lists of blocks from the various
* spaces together.
*
* Additionally, we record the free space frontier of the heap, as
* well as the address of the first object within a block, which is
* required to copy objects following a large object (not currently
* implemented). This is stored in the heap source structure. This
* should be moved elsewhere to support in-line allocations from Java
* threads.
*
* Allocation requests are satisfied by reserving storage from one or
* more contiguous blocks. Objects that are small enough to fit
* inside a block are packed together within a block. Objects that
* are larger than a block are allocated from contiguous sequences of
* blocks. When half the available blocks are filled, a garbage
* collection occurs. We "flip" spaces (exchange from- and to-space),
* copy live objects into to space, and perform pointer adjustment.
*
* Copying is made more complicated by the requirement that some
* objects must not be moved. This property is known as "pinning".
* These objects must be dealt with specially. We use Bartlett's
* scheme; blocks containing such objects are grayed (promoted) at the
* start of a garbage collection. By virtue of this trick, tracing
* from the roots proceeds as usual but all objects on those pages are
* considered promoted and therefore not moved.
*
* TODO: there is sufficient information within the garbage collector
* to implement Attardi's scheme for evacuating unpinned objects from
* a page that is otherwise pinned. This would eliminate false
* retention caused by the large pinning granularity.
*
* We need a scheme for medium and large objects. Ignore that for
* now, we can return to this later.
*
* Eventually we need to worry about promoting objects out of the
* copy-collected heap (tenuring) into a less volatile space. Copying
* may not always be the best policy for such spaces. We should
* consider a variant of mark, sweep, compact.
*
* The block scheme allows us to use VM page faults to maintain a
* write barrier. Consider having a special leaf state for a page.
*
* Bibliography:
*
* C. J. Cheney. 1970. A non-recursive list compacting
* algorithm. CACM. 13-11 pp677--678.
*
* Joel F. Bartlett. 1988. Compacting Garbage Collection with
* Ambiguous Roots. Digital Equipment Corporation.
*
* Joel F. Bartlett. 1989. Mostly-Copying Garbage Collection Picks Up
* Generations and C++. Digital Equipment Corporation.
*
* G. May Yip. 1991. Incremental, Generational Mostly-Copying Garbage
* Collection in Uncooperative Environments. Digital Equipment
* Corporation.
*
* Giuseppe Attardi, Tito Flagella. 1994. A Customisable Memory
* Management Framework. TR-94-010
*
* Giuseppe Attardi, Tito Flagella, Pietro Iglio. 1998. A customisable
* memory management framework for C++. Software -- Practice and
* Experience. 28(11), 1143-1183.
*
*/
#define ARRAYSIZE(x) (sizeof(x) / sizeof(x[0]))
#if 0
#define LOG_ALLOC LOGI
#define LOG_PIN LOGI
#define LOG_PROM LOGI
#define LOG_REF LOGI
#define LOG_SCAV LOGI
#define LOG_TRAN LOGI
#define LOG_VER LOGI
#else
#define LOG_ALLOC(...) ((void)0)
#define LOG_PIN(...) ((void)0)
#define LOG_PROM(...) ((void)0)
#define LOG_REF(...) ((void)0)
#define LOG_SCAV(...) ((void)0)
#define LOG_TRAN(...) ((void)0)
#define LOG_VER(...) ((void)0)
#endif
static void enqueueBlock(HeapSource *heapSource, size_t block);
static void scavengeReference(Object **obj);
static bool toSpaceContains(const void *addr);
static bool fromSpaceContains(const void *addr);
static size_t sumHeapBitmap(const HeapBitmap *bitmap);
static size_t objectSize(const Object *obj);
static void scavengeDataObject(Object *obj);
static void scavengeBlockQueue(void);
/*
* We use 512-byte blocks.
*/
enum { BLOCK_SHIFT = 9 };
enum { BLOCK_SIZE = 1 << BLOCK_SHIFT };
/*
* Space identifiers, stored into the blockSpace array.
*/
enum {
BLOCK_FREE = 0,
BLOCK_FROM_SPACE = 1,
BLOCK_TO_SPACE = 2,
BLOCK_CONTINUED = 7
};
/*
* Alignment for all allocations, in bytes.
*/
enum { ALLOC_ALIGNMENT = 8 };
/*
* Sentinel value for the queue end.
*/
#define QUEUE_TAIL (~(size_t)0)
struct HeapSource {
/* The base address of backing store. */
u1 *blockBase;
/* Total number of blocks available for allocation. */
size_t totalBlocks;
size_t allocBlocks;
/*
* The scavenger work queue. Implemented as an array of index
* values into the queue.
*/
size_t *blockQueue;
/*
* Base and limit blocks. Basically the shifted start address of
* the block. We convert blocks to a relative number when
* indexing in the block queue. TODO: make the block queue base
* relative rather than the index into the block queue.
*/
size_t baseBlock, limitBlock;
size_t queueHead;
size_t queueTail;
size_t queueSize;
/* The space of the current block 0 (free), 1 or 2. */
char *blockSpace;
/* Start of free space in the current block. */
u1 *allocPtr;
/* Exclusive limit of free space in the current block. */
u1 *allocLimit;
HeapBitmap allocBits;
/*
* The starting size of the heap. This value is the same as the
* value provided to the -Xms flag.
*/
size_t minimumSize;
/*
* The maximum size of the heap. This value is the same as the
* -Xmx flag.
*/
size_t maximumSize;
/*
* The current, committed size of the heap. At present, this is
* equivalent to the maximumSize.
*/
size_t currentSize;
size_t bytesAllocated;
};
static unsigned long alignDown(unsigned long x, unsigned long n)
{
return x & -n;
}
static unsigned long alignUp(unsigned long x, unsigned long n)
{
return alignDown(x + (n - 1), n);
}
static void describeBlocks(const HeapSource *heapSource)
{
size_t i;
for (i = 0; i < heapSource->totalBlocks; ++i) {
if ((i % 32) == 0) putchar('\n');
printf("%d ", heapSource->blockSpace[i]);
}
putchar('\n');
}
/*
* Virtual memory interface.
*/
static void *virtualAlloc(size_t length)
{
void *addr;
int flags, prot;
flags = MAP_PRIVATE | MAP_ANONYMOUS;
prot = PROT_READ | PROT_WRITE;
addr = mmap(NULL, length, prot, flags, -1, 0);
if (addr == MAP_FAILED) {
LOGE_HEAP("mmap: %s", strerror(errno));
addr = NULL;
}
return addr;
}
static void virtualFree(void *addr, size_t length)
{
int res;
assert(addr != NULL);
assert((uintptr_t)addr % SYSTEM_PAGE_SIZE == 0);
res = munmap(addr, length);
if (res == -1) {
LOGE_HEAP("munmap: %s", strerror(errno));
}
}
#ifndef NDEBUG
static int isValidAddress(const HeapSource *heapSource, const u1 *addr)
{
size_t block;
block = (uintptr_t)addr >> BLOCK_SHIFT;
return heapSource->baseBlock <= block &&
heapSource->limitBlock > block;
}
#endif
/*
* Iterate over the block map looking for a contiguous run of free
* blocks.
*/
static void *allocateBlocks(HeapSource *heapSource, size_t blocks)
{
void *addr;
size_t allocBlocks, totalBlocks;
size_t i, j;
allocBlocks = heapSource->allocBlocks;
totalBlocks = heapSource->totalBlocks;
/* Check underflow. */
assert(blocks != 0);
/* Check overflow. */
if (allocBlocks + blocks > totalBlocks / 2) {
return NULL;
}
/* Scan block map. */
for (i = 0; i < totalBlocks; ++i) {
/* Check fit. */
for (j = 0; j < blocks; ++j) { /* runs over totalBlocks */
if (heapSource->blockSpace[i+j] != BLOCK_FREE) {
break;
}
}
/* No fit? */
if (j != blocks) {
i += j;
continue;
}
/* Fit, allocate. */
heapSource->blockSpace[i] = BLOCK_TO_SPACE; /* why to-space? */
for (j = 1; j < blocks; ++j) {
heapSource->blockSpace[i+j] = BLOCK_CONTINUED;
}
heapSource->allocBlocks += blocks;
addr = &heapSource->blockBase[i*BLOCK_SIZE];
memset(addr, 0, blocks*BLOCK_SIZE);
/* Collecting? */
if (heapSource->queueHead != QUEUE_TAIL) {
LOG_ALLOC("allocateBlocks allocBlocks=%zu,block#=%zu", heapSource->allocBlocks, i);
/*
* This allocated was on behalf of the transporter when it
* shaded a white object gray. We enqueue the block so
* the scavenger can further shade the gray objects black.
*/
enqueueBlock(heapSource, i);
}
return addr;
}
/* Insufficient space, fail. */
LOGE("Insufficient space, %zu blocks, %zu blocks allocated and %zu bytes allocated",
heapSource->totalBlocks,
heapSource->allocBlocks,
heapSource->bytesAllocated);
return NULL;
}
/* Converts an absolute address to a relative block number. */
static size_t addressToBlock(const HeapSource *heapSource, const void *addr)
{
assert(heapSource != NULL);
assert(isValidAddress(heapSource, addr));
return (((uintptr_t)addr) >> BLOCK_SHIFT) - heapSource->baseBlock;
}
/* Converts a relative block number to an absolute address. */
static u1 *blockToAddress(const HeapSource *heapSource, size_t block)
{
u1 *addr;
addr = (u1 *) (((uintptr_t) heapSource->baseBlock + block) * BLOCK_SIZE);
assert(isValidAddress(heapSource, addr));
return addr;
}
static void clearBlock(HeapSource *heapSource, size_t block)
{
u1 *addr;
size_t i;
assert(heapSource != NULL);
assert(block < heapSource->totalBlocks);
addr = heapSource->blockBase + block*BLOCK_SIZE;
memset(addr, 0xCC, BLOCK_SIZE);
for (i = 0; i < BLOCK_SIZE; i += 8) {
dvmHeapBitmapClearObjectBit(&heapSource->allocBits, addr + i);
}
}
static void clearFromSpace(HeapSource *heapSource)
{
size_t i, count;
assert(heapSource != NULL);
i = count = 0;
while (i < heapSource->totalBlocks) {
if (heapSource->blockSpace[i] != BLOCK_FROM_SPACE) {
++i;
continue;
}
heapSource->blockSpace[i] = BLOCK_FREE;
clearBlock(heapSource, i);
++i;
++count;
while (i < heapSource->totalBlocks &&
heapSource->blockSpace[i] == BLOCK_CONTINUED) {
heapSource->blockSpace[i] = BLOCK_FREE;
clearBlock(heapSource, i);
++i;
++count;
}
}
LOG_SCAV("freed %zu blocks (%zu bytes)", count, count*BLOCK_SIZE);
}
/*
* Appends the given block to the block queue. The block queue is
* processed in-order by the scavenger.
*/
static void enqueueBlock(HeapSource *heapSource, size_t block)
{
assert(heapSource != NULL);
assert(block < heapSource->totalBlocks);
if (heapSource->queueHead != QUEUE_TAIL) {
heapSource->blockQueue[heapSource->queueTail] = block;
} else {
heapSource->queueHead = block;
}
heapSource->blockQueue[block] = QUEUE_TAIL;
heapSource->queueTail = block;
++heapSource->queueSize;
}
/*
* Grays all objects within the block corresponding to the given
* address.
*/
static void promoteBlockByAddr(HeapSource *heapSource, const void *addr)
{
size_t block;
block = addressToBlock(heapSource, (const u1 *)addr);
if (heapSource->blockSpace[block] != BLOCK_TO_SPACE) {
// LOG_PROM("promoting block %zu %d @ %p", block, heapSource->blockSpace[block], obj);
heapSource->blockSpace[block] = BLOCK_TO_SPACE;
enqueueBlock(heapSource, block);
/* TODO(cshapiro): count continued blocks?*/
heapSource->allocBlocks += 1;
} else {
// LOG_PROM("NOT promoting block %zu %d @ %p", block, heapSource->blockSpace[block], obj);
}
}
GcHeap *dvmHeapSourceStartup(size_t startSize, size_t absoluteMaxSize)
{
GcHeap* gcHeap;
HeapSource *heapSource;
assert(startSize <= absoluteMaxSize);
heapSource = malloc(sizeof(*heapSource));
assert(heapSource != NULL);
memset(heapSource, 0, sizeof(*heapSource));
heapSource->minimumSize = alignUp(startSize, BLOCK_SIZE);
heapSource->maximumSize = alignUp(absoluteMaxSize, BLOCK_SIZE);
heapSource->currentSize = heapSource->maximumSize;
/* Allocate underlying storage for blocks. */
heapSource->blockBase = virtualAlloc(heapSource->maximumSize);
assert(heapSource->blockBase != NULL);
heapSource->baseBlock = (uintptr_t) heapSource->blockBase >> BLOCK_SHIFT;
heapSource->limitBlock = ((uintptr_t) heapSource->blockBase + heapSource->maximumSize) >> BLOCK_SHIFT;
heapSource->allocBlocks = 0;
heapSource->totalBlocks = (heapSource->limitBlock - heapSource->baseBlock);
assert(heapSource->totalBlocks = heapSource->maximumSize / BLOCK_SIZE);
{
size_t size = sizeof(heapSource->blockQueue[0]);
heapSource->blockQueue = malloc(heapSource->totalBlocks*size);
assert(heapSource->blockQueue != NULL);
memset(heapSource->blockQueue, 0xCC, heapSource->totalBlocks*size);
heapSource->queueHead = QUEUE_TAIL;
}
/* Byte indicating space residence or free status of block. */
{
size_t size = sizeof(heapSource->blockSpace[0]);
heapSource->blockSpace = malloc(heapSource->totalBlocks*size);
assert(heapSource->blockSpace != NULL);
memset(heapSource->blockSpace, 0, heapSource->totalBlocks*size);
}
dvmHeapBitmapInit(&heapSource->allocBits,
heapSource->blockBase,
heapSource->maximumSize,
"blockBase");
/* Initialize allocation pointers. */
heapSource->allocPtr = allocateBlocks(heapSource, 1);
heapSource->allocLimit = heapSource->allocPtr + BLOCK_SIZE;
gcHeap = malloc(sizeof(*gcHeap));
assert(gcHeap != NULL);
memset(gcHeap, 0, sizeof(*gcHeap));
gcHeap->heapSource = heapSource;
return gcHeap;
}
/*
* Perform any required heap initializations after forking from the
* zygote process. This is a no-op for the time being. Eventually
* this will demarcate the shared region of the heap.
*/
bool dvmHeapSourceStartupAfterZygote(void)
{
return true;
}
bool dvmHeapSourceStartupBeforeFork(void)
{
assert(!"implemented");
return false;
}
void dvmHeapSourceShutdown(GcHeap **gcHeap)
{
if (*gcHeap == NULL || (*gcHeap)->heapSource == NULL)
return;
free((*gcHeap)->heapSource->blockQueue);
free((*gcHeap)->heapSource->blockSpace);
virtualFree((*gcHeap)->heapSource->blockBase,
(*gcHeap)->heapSource->maximumSize);
free((*gcHeap)->heapSource);
(*gcHeap)->heapSource = NULL;
free(*gcHeap);
*gcHeap = NULL;
}
size_t dvmHeapSourceGetValue(enum HeapSourceValueSpec spec,
size_t perHeapStats[],
size_t arrayLen)
{
HeapSource *heapSource;
size_t value;
heapSource = gDvm.gcHeap->heapSource;
switch (spec) {
case HS_EXTERNAL_BYTES_ALLOCATED:
value = 0;
break;
case HS_EXTERNAL_LIMIT:
value = 0;
break;
case HS_FOOTPRINT:
value = heapSource->maximumSize;
break;
case HS_ALLOWED_FOOTPRINT:
value = heapSource->maximumSize;
break;
case HS_BYTES_ALLOCATED:
value = heapSource->bytesAllocated;
break;
case HS_OBJECTS_ALLOCATED:
value = sumHeapBitmap(&heapSource->allocBits);
break;
default:
assert(!"implemented");
value = 0;
}
if (perHeapStats) {
*perHeapStats = value;
}
return value;
}
/*
* Performs a shallow copy of the allocation bitmap into the given
* vector of heap bitmaps.
*/
void dvmHeapSourceGetObjectBitmaps(HeapBitmap objBits[], HeapBitmap markBits[],
size_t numHeaps)
{
assert(!"implemented");
}
HeapBitmap *dvmHeapSourceGetLiveBits(void)
{
return &gDvm.gcHeap->heapSource->allocBits;
}
/*
* Allocate the specified number of bytes from the heap. The
* allocation cursor points into a block of free storage. If the
* given allocation fits in the remaining space of the block, we
* advance the cursor and return a pointer to the free storage. If
* the allocation cannot fit in the current block but is smaller than
* a block we request a new block and allocate from it instead. If
* the allocation is larger than a block we must allocate from a span
* of contiguous blocks.
*/
void *dvmHeapSourceAlloc(size_t length)
{
HeapSource *heapSource;
unsigned char *addr;
size_t aligned, available, blocks;
heapSource = gDvm.gcHeap->heapSource;
assert(heapSource != NULL);
assert(heapSource->allocPtr != NULL);
assert(heapSource->allocLimit != NULL);
aligned = alignUp(length, ALLOC_ALIGNMENT);
available = heapSource->allocLimit - heapSource->allocPtr;
/* Try allocating inside the current block. */
if (aligned <= available) {
addr = heapSource->allocPtr;
heapSource->allocPtr += aligned;
heapSource->bytesAllocated += aligned;
dvmHeapBitmapSetObjectBit(&heapSource->allocBits, addr);
return addr;
}
/* Try allocating in a new block. */
if (aligned <= BLOCK_SIZE) {
addr = allocateBlocks(heapSource, 1);
if (addr != NULL) {
heapSource->allocLimit = addr + BLOCK_SIZE;
heapSource->allocPtr = addr + aligned;
heapSource->bytesAllocated += aligned;
dvmHeapBitmapSetObjectBit(&heapSource->allocBits, addr);
/* TODO(cshapiro): pad out the current block. */
}
return addr;
}
/* Try allocating in a span of blocks. */
blocks = alignUp(aligned, BLOCK_SIZE) / BLOCK_SIZE;
addr = allocateBlocks(heapSource, blocks);
/* Propagate failure upward. */
if (addr != NULL) {
heapSource->bytesAllocated += aligned;
dvmHeapBitmapSetObjectBit(&heapSource->allocBits, addr);
/* TODO(cshapiro): pad out free space in the last block. */
}
return addr;
}
void *dvmHeapSourceAllocAndGrow(size_t size)
{
return dvmHeapSourceAlloc(size);
}
/* TODO: refactor along with dvmHeapSourceAlloc */
void *allocateGray(size_t size)
{
HeapSource *heapSource;
void *addr;
size_t block;
/* TODO: add a check that we are in a GC. */
heapSource = gDvm.gcHeap->heapSource;
addr = dvmHeapSourceAlloc(size);
assert(addr != NULL);
block = addressToBlock(heapSource, (const u1 *)addr);
if (heapSource->queueHead == QUEUE_TAIL) {
/*
* Forcibly append the underlying block to the queue. This
* condition occurs when referents are transported following
* the initial trace.
*/
enqueueBlock(heapSource, block);
LOG_PROM("forced promoting block %zu %d @ %p", block, heapSource->blockSpace[block], addr);
}
return addr;
}
bool dvmHeapSourceContainsAddress(const void *ptr)
{
HeapSource *heapSource = gDvm.gcHeap->heapSource;
return dvmHeapBitmapCoversAddress(&heapSource->allocBits, ptr);
}
/*
* Returns true if the given address is within the heap and points to
* the header of a live object.
*/
bool dvmHeapSourceContains(const void *addr)
{
HeapSource *heapSource;
HeapBitmap *bitmap;
heapSource = gDvm.gcHeap->heapSource;
bitmap = &heapSource->allocBits;
if (!dvmHeapBitmapCoversAddress(bitmap, addr)) {
return false;
} else {
return dvmHeapBitmapIsObjectBitSet(bitmap, addr);
}
}
bool dvmHeapSourceGetPtrFlag(const void *ptr, enum HeapSourcePtrFlag flag)
{
assert(!"implemented");
return false;
}
size_t dvmHeapSourceChunkSize(const void *ptr)
{
assert(!"implemented");
return 0;
}
size_t dvmHeapSourceFootprint(void)
{
assert(!"implemented");
return 0;
}
/*
* Returns the "ideal footprint" which appears to be the number of
* bytes currently committed to the heap. This starts out at the
* start size of the heap and grows toward the maximum size.
*/
size_t dvmHeapSourceGetIdealFootprint(void)
{
return gDvm.gcHeap->heapSource->currentSize;
}
float dvmGetTargetHeapUtilization(void)
{
return 0.5f;
}
void dvmSetTargetHeapUtilization(float newTarget)
{
assert(newTarget > 0.0f && newTarget < 1.0f);
}
size_t dvmMinimumHeapSize(size_t size, bool set)
{
return gDvm.gcHeap->heapSource->minimumSize;
}
/*
* Expands the size of the heap after a collection. At present we
* commit the pages for maximum size of the heap so this routine is
* just a no-op. Eventually, we will either allocate or commit pages
* on an as-need basis.
*/
void dvmHeapSourceGrowForUtilization(void)
{
/* do nothing */
}
void dvmHeapSourceTrim(size_t bytesTrimmed[], size_t arrayLen)
{
/* do nothing */
}
void dvmHeapSourceWalk(void (*callback)(const void *chunkptr, size_t chunklen,
const void *userptr, size_t userlen,
void *arg),
void *arg)
{
assert(!"implemented");
}
size_t dvmHeapSourceGetNumHeaps(void)
{
return 1;
}
bool dvmTrackExternalAllocation(size_t n)
{
/* do nothing */
return true;
}
void dvmTrackExternalFree(size_t n)
{
/* do nothing */
}
size_t dvmGetExternalBytesAllocated(void)
{
assert(!"implemented");
return 0;
}
void dvmHeapSourceFlip(void)
{
HeapSource *heapSource;
size_t i;
heapSource = gDvm.gcHeap->heapSource;
/* Reset the block queue. */
heapSource->allocBlocks = 0;
heapSource->queueSize = 0;
heapSource->queueHead = QUEUE_TAIL;
/* TODO(cshapiro): pad the current (prev) block. */
heapSource->allocPtr = NULL;
heapSource->allocLimit = NULL;
/* Whiten all allocated blocks. */
for (i = 0; i < heapSource->totalBlocks; ++i) {
if (heapSource->blockSpace[i] == BLOCK_TO_SPACE) {
heapSource->blockSpace[i] = BLOCK_FROM_SPACE;
}
}
}
static void room(size_t *alloc, size_t *avail, size_t *total)
{
HeapSource *heapSource;
heapSource = gDvm.gcHeap->heapSource;
*total = heapSource->totalBlocks*BLOCK_SIZE;
*alloc = heapSource->allocBlocks*BLOCK_SIZE;
*avail = *total - *alloc;
}
static bool isSpaceInternal(u1 *addr, int space)
{
HeapSource *heapSource;
u1 *base, *limit;
size_t offset;
char space2;
heapSource = gDvm.gcHeap->heapSource;
base = heapSource->blockBase;
assert(addr >= base);
limit = heapSource->blockBase + heapSource->maximumSize;
assert(addr < limit);
offset = addr - base;
space2 = heapSource->blockSpace[offset >> BLOCK_SHIFT];
return space == space2;
}
static bool fromSpaceContains(const void *addr)
{
return isSpaceInternal((u1 *)addr, BLOCK_FROM_SPACE);
}
static bool toSpaceContains(const void *addr)
{
return isSpaceInternal((u1 *)addr, BLOCK_TO_SPACE);
}
/*
* Notifies the collector that the object at the given address must
* remain stationary during the current collection.
*/
static void pinObject(const Object *obj)
{
promoteBlockByAddr(gDvm.gcHeap->heapSource, obj);
}
static size_t sumHeapBitmap(const HeapBitmap *bitmap)
{
size_t i, sum;
sum = 0;
for (i = 0; i < bitmap->bitsLen >> 2; ++i) {
sum += CLZ(bitmap->bits[i]);
}
return sum;
}
/*
* Miscellaneous functionality.
*/
static int isForward(const void *addr)
{
return (uintptr_t)addr & 0x1;
}
static void setForward(const void *toObj, void *fromObj)
{
*(unsigned long *)fromObj = (uintptr_t)toObj | 0x1;
}
static void* getForward(const void *fromObj)
{
return (void *)((uintptr_t)fromObj & ~0x1);
}
/* Beware, uses the same encoding as a forwarding pointers! */
static int isPermanentString(const StringObject *obj) {
return (uintptr_t)obj & 0x1;
}
static void* getPermanentString(const StringObject *obj)
{
return (void *)((uintptr_t)obj & ~0x1);
}
/*
* Scavenging and transporting routines follow. A transporter grays
* an object. A scavenger blackens an object. We define these
* routines for each fundamental object type. Dispatch is performed
* in scavengeObject.
*/
/*
* Class object scavenging.
*/
static void scavengeClassObject(ClassObject *obj)
{
int i;
LOG_SCAV("scavengeClassObject(obj=%p)", obj);
assert(obj != NULL);
assert(obj->obj.clazz != NULL);
assert(obj->obj.clazz->descriptor != NULL);
assert(!strcmp(obj->obj.clazz->descriptor, "Ljava/lang/Class;"));
assert(obj->descriptor != NULL);
LOG_SCAV("scavengeClassObject: descriptor='%s',vtableCount=%zu",
obj->descriptor, obj->vtableCount);
/* Delegate class object and instance field scavenging. */
scavengeDataObject((Object *)obj);
/* Scavenge the array element class object. */
if (IS_CLASS_FLAG_SET(obj, CLASS_ISARRAY)) {
scavengeReference((Object **)(void *)&obj->elementClass);
}
/* Scavenge the superclass. */
scavengeReference((Object **)(void *)&obj->super);
/* Scavenge the class loader. */
scavengeReference(&obj->classLoader);
/* Scavenge static fields. */
for (i = 0; i < obj->sfieldCount; ++i) {
char ch = obj->sfields[i].field.signature[0];
if (ch == '[' || ch == 'L') {
scavengeReference((Object **)(void *)&obj->sfields[i].value.l);
}
}
/* Scavenge interface class objects. */
for (i = 0; i < obj->interfaceCount; ++i) {
scavengeReference((Object **) &obj->interfaces[i]);
}
}
/*
* Array object scavenging.
*/
static size_t scavengeArrayObject(ArrayObject *array)
{
size_t i, length;
LOG_SCAV("scavengeArrayObject(array=%p)", array);
/* Scavenge the class object. */
assert(toSpaceContains(array));
assert(array != NULL);
assert(array->obj.clazz != NULL);
scavengeReference((Object **) array);
length = dvmArrayObjectSize(array);
/* Scavenge the array contents. */
if (IS_CLASS_FLAG_SET(array->obj.clazz, CLASS_ISOBJECTARRAY)) {
Object **contents = (Object **)array->contents;
for (i = 0; i < array->length; ++i) {
scavengeReference(&contents[i]);
}
}
return length;
}
/*
* Reference object scavenging.
*/
static int getReferenceFlags(const Object *obj)
{
int flags;
flags = CLASS_ISREFERENCE |
CLASS_ISWEAKREFERENCE |
CLASS_ISPHANTOMREFERENCE;
return GET_CLASS_FLAG_GROUP(obj->clazz, flags);
}
static int isSoftReference(const Object *obj)
{
return getReferenceFlags(obj) == CLASS_ISREFERENCE;
}
static int isWeakReference(const Object *obj)
{
return getReferenceFlags(obj) & CLASS_ISWEAKREFERENCE;
}
#ifndef NDEBUG
static bool isPhantomReference(const Object *obj)
{
return getReferenceFlags(obj) & CLASS_ISPHANTOMREFERENCE;
}
#endif
/*
* Returns true if the reference was registered with a reference queue
* but has not yet been appended to it.
*/
static bool isReferenceEnqueuable(const Object *ref)
{
Object *queue, *queueNext;
queue = dvmGetFieldObject(ref, gDvm.offJavaLangRefReference_queue);
queueNext = dvmGetFieldObject(ref, gDvm.offJavaLangRefReference_queueNext);
if (queue == NULL || queueNext != NULL) {
/*
* There is no queue, or the reference has already
* been enqueued. The Reference.enqueue() method
* will do nothing even if we call it.
*/
return false;
}
/*
* We need to call enqueue(), but if we called it from
* here we'd probably deadlock. Schedule a call.
*/
return true;
}
/*
* Schedules a reference to be appended to its reference queue.
*/
static void enqueueReference(Object *ref)
{
assert(ref != NULL);
assert(dvmGetFieldObject(ref, gDvm.offJavaLangRefReference_queue) != NULL);
assert(dvmGetFieldObject(ref, gDvm.offJavaLangRefReference_queueNext) == NULL);
if (!dvmHeapAddRefToLargeTable(&gDvm.gcHeap->referenceOperations, ref)) {
LOGE("no room for any more reference operations");
dvmAbort();
}
}
/*
* Sets the referent field of a reference object to NULL.
*/
static void clearReference(Object *obj)
{
dvmSetFieldObject(obj, gDvm.offJavaLangRefReference_referent, NULL);
}
/*
* Clears reference objects with white referents.
*/
void clearWhiteReferences(Object **list)
{
size_t referentOffset, queueNextOffset;
bool doSignal;
queueNextOffset = gDvm.offJavaLangRefReference_queueNext;
referentOffset = gDvm.offJavaLangRefReference_referent;
doSignal = false;
while (*list != NULL) {
Object *ref = *list;
JValue *field = dvmFieldPtr(ref, referentOffset);
Object *referent = field->l;
*list = dvmGetFieldObject(ref, queueNextOffset);
dvmSetFieldObject(ref, queueNextOffset, NULL);
assert(referent != NULL);
if (isForward(referent->clazz)) {
field->l = referent = getForward(referent->clazz);
continue;
}
if (fromSpaceContains(referent)) {
/* Referent is white, clear it. */
clearReference(ref);
if (isReferenceEnqueuable(ref)) {
enqueueReference(ref);
doSignal = true;
}
}
}
/*
* If we cleared a reference with a reference queue we must notify
* the heap worker to append the reference.
*/
if (doSignal) {
dvmSignalHeapWorker(false);
}
assert(*list == NULL);
}
/*
* Blackens referents subject to the soft reference preservation
* policy.
*/
void preserveSoftReferences(Object **list)
{
Object *ref;
Object *prev, *next;
size_t referentOffset, queueNextOffset;
unsigned counter;
bool white;
queueNextOffset = gDvm.offJavaLangRefReference_queueNext;
referentOffset = gDvm.offJavaLangRefReference_referent;
counter = 0;
prev = next = NULL;
ref = *list;
while (ref != NULL) {
JValue *field = dvmFieldPtr(ref, referentOffset);
Object *referent = field->l;
next = dvmGetFieldObject(ref, queueNextOffset);
assert(referent != NULL);
if (isForward(referent->clazz)) {
/* Referent is black. */
field->l = referent = getForward(referent->clazz);
white = false;
} else {
white = fromSpaceContains(referent);
}
if (!white && ((++counter) & 1)) {
/* Referent is white and biased toward saving, gray it. */
scavengeReference((Object **)(void *)&field->l);
white = true;
}
if (white) {
/* Referent is black, unlink it. */
if (prev != NULL) {
dvmSetFieldObject(ref, queueNextOffset, NULL);
dvmSetFieldObject(prev, queueNextOffset, next);
}
} else {
/* Referent is white, skip over it. */
prev = ref;
}
ref = next;
}
/*
* Restart the trace with the newly gray references added to the
* root set.
*/
scavengeBlockQueue();
}
void processFinalizableReferences(void)
{
HeapRefTable newPendingRefs;
LargeHeapRefTable *finRefs = gDvm.gcHeap->finalizableRefs;
Object **ref;
Object **lastRef;
size_t totalPendCount;
/*
* All strongly, reachable objects are black.
* Any white finalizable objects need to be finalized.
*/
/* Create a table that the new pending refs will
* be added to.
*/
if (!dvmHeapInitHeapRefTable(&newPendingRefs)) {
//TODO: mark all finalizable refs and hope that
// we can schedule them next time. Watch out,
// because we may be expecting to free up space
// by calling finalizers.
LOG_REF("no room for pending finalizations\n");
dvmAbort();
}
/*
* Walk through finalizableRefs and move any white references to
* the list of new pending refs.
*/
totalPendCount = 0;
while (finRefs != NULL) {
Object **gapRef;
size_t newPendCount = 0;
gapRef = ref = finRefs->refs.table;
lastRef = finRefs->refs.nextEntry;
while (ref < lastRef) {
if (fromSpaceContains(*ref)) {
if (!dvmHeapAddToHeapRefTable(&newPendingRefs, *ref)) {
//TODO: add the current table and allocate
// a new, smaller one.
LOG_REF("no room for any more pending finalizations: %zd\n",
dvmHeapNumHeapRefTableEntries(&newPendingRefs));
dvmAbort();
}
newPendCount++;
} else {
/* This ref is black, so will remain on finalizableRefs.
*/
if (newPendCount > 0) {
/* Copy it up to fill the holes.
*/
*gapRef++ = *ref;
} else {
/* No holes yet; don't bother copying.
*/
gapRef++;
}
}
ref++;
}
finRefs->refs.nextEntry = gapRef;
//TODO: if the table is empty when we're done, free it.
totalPendCount += newPendCount;
finRefs = finRefs->next;
}
LOG_REF("%zd finalizers triggered.\n", totalPendCount);
if (totalPendCount == 0) {
/* No objects required finalization.
* Free the empty temporary table.
*/
dvmClearReferenceTable(&newPendingRefs);
return;
}
/* Add the new pending refs to the main list.
*/
if (!dvmHeapAddTableToLargeTable(&gDvm.gcHeap->pendingFinalizationRefs,
&newPendingRefs))
{
LOG_REF("can't insert new pending finalizations\n");
dvmAbort();
}
//TODO: try compacting the main list with a memcpy loop
/* Blacken the refs we just moved; we don't want them or their
* children to get swept yet.
*/
ref = newPendingRefs.table;
lastRef = newPendingRefs.nextEntry;
assert(ref < lastRef);
HPROF_SET_GC_SCAN_STATE(HPROF_ROOT_FINALIZING, 0);
while (ref < lastRef) {
scavengeReference(ref);
ref++;
}
HPROF_CLEAR_GC_SCAN_STATE();
scavengeBlockQueue();
dvmSignalHeapWorker(false);
}
/*
* If a reference points to from-space and has been forwarded, we snap
* the pointer to its new to-space address. If the reference points
* to an unforwarded from-space address we must enqueue the reference
* for later processing. TODO: implement proper reference processing
* and move the referent scavenging elsewhere.
*/
static void scavengeReferenceObject(Object *obj)
{
Object *referent;
Object **queue;
size_t referentOffset, queueNextOffset;
assert(obj != NULL);
LOG_SCAV("scavengeReferenceObject(obj=%p),'%s'", obj, obj->clazz->descriptor);
scavengeDataObject(obj);
referentOffset = gDvm.offJavaLangRefReference_referent;
referent = dvmGetFieldObject(obj, referentOffset);
if (referent == NULL || toSpaceContains(referent)) {
return;
}
if (isSoftReference(obj)) {
queue = &gDvm.gcHeap->softReferences;
} else if (isWeakReference(obj)) {
queue = &gDvm.gcHeap->weakReferences;
} else {
assert(isPhantomReference(obj));
queue = &gDvm.gcHeap->phantomReferences;
}
queueNextOffset = gDvm.offJavaLangRefReference_queueNext;
dvmSetFieldObject(obj, queueNextOffset, *queue);
*queue = obj;
LOG_SCAV("scavengeReferenceObject: enqueueing %p", obj);
}
/*
* Data object scavenging.
*/
static void scavengeDataObject(Object *obj)
{
ClassObject *clazz;
int i;
// LOG_SCAV("scavengeDataObject(obj=%p)", obj);
assert(obj != NULL);
assert(obj->clazz != NULL);
assert(obj->clazz->objectSize != 0);
assert(toSpaceContains(obj));
/* Scavenge the class object. */
clazz = obj->clazz;
scavengeReference((Object **) obj);
/* Scavenge instance fields. */
if (clazz->refOffsets != CLASS_WALK_SUPER) {
size_t refOffsets = clazz->refOffsets;
while (refOffsets != 0) {
size_t rshift = CLZ(refOffsets);
size_t offset = CLASS_OFFSET_FROM_CLZ(rshift);
Object **ref = (Object **)((u1 *)obj + offset);
scavengeReference(ref);
refOffsets &= ~(CLASS_HIGH_BIT >> rshift);
}
} else {
for (; clazz != NULL; clazz = clazz->super) {
InstField *field = clazz->ifields;
for (i = 0; i < clazz->ifieldRefCount; ++i, ++field) {
size_t offset = field->byteOffset;
Object **ref = (Object **)((u1 *)obj + offset);
scavengeReference(ref);
}
}
}
}
static Object *transportObject(const Object *fromObj)
{
Object *toObj;
size_t allocSize, copySize;
LOG_TRAN("transportObject(fromObj=%p) allocBlocks=%zu",
fromObj,
gDvm.gcHeap->heapSource->allocBlocks);
assert(fromObj != NULL);
assert(fromSpaceContains(fromObj));
allocSize = copySize = objectSize(fromObj);
if (LW_HASH_STATE(fromObj->lock) != LW_HASH_STATE_UNHASHED) {
/*
* The object has been hashed or hashed and moved. We must
* reserve an additional word for a hash code.
*/
allocSize += sizeof(u4);
}
if (LW_HASH_STATE(fromObj->lock) == LW_HASH_STATE_HASHED_AND_MOVED) {
/*
* The object has its hash code allocated. Ensure the hash
* code is copied along with the instance data.
*/
copySize += sizeof(u4);
}
/* TODO(cshapiro): don't copy, re-map large data objects. */
assert(copySize <= allocSize);
toObj = allocateGray(allocSize);
assert(toObj != NULL);
assert(toSpaceContains(toObj));
memcpy(toObj, fromObj, copySize);
if (LW_HASH_STATE(fromObj->lock) == LW_HASH_STATE_HASHED) {
/*
* The object has had its hash code exposed. Append it to the
* instance and set a bit so we know to look for it there.
*/
*(u4 *)(((char *)toObj) + copySize) = (u4)fromObj >> 3;
toObj->lock |= LW_HASH_STATE_HASHED_AND_MOVED << LW_HASH_STATE_SHIFT;
}
LOG_TRAN("transportObject: from %p/%zu to %p/%zu (%zu,%zu) %s",
fromObj, addressToBlock(gDvm.gcHeap->heapSource,fromObj),
toObj, addressToBlock(gDvm.gcHeap->heapSource,toObj),
copySize, allocSize, copySize < allocSize ? "DIFFERENT" : "");
return toObj;
}
/*
* Generic reference scavenging.
*/
/*
* Given a reference to an object, the scavenge routine will gray the
* reference. Any objects pointed to by the scavenger object will be
* transported to new space and a forwarding pointer will be installed
* in the header of the object.
*/
/*
* Blacken the given pointer. If the pointer is in from space, it is
* transported to new space. If the object has a forwarding pointer
* installed it has already been transported and the referent is
* snapped to the new address.
*/
static void scavengeReference(Object **obj)
{
ClassObject *clazz;
Object *fromObj, *toObj;
assert(obj);
if (*obj == NULL) return;
assert(dvmIsValidObject(*obj));
/* The entire block is black. */
if (toSpaceContains(*obj)) {
LOG_SCAV("scavengeReference skipping pinned object @ %p", *obj);
return;
}
LOG_SCAV("scavengeReference(*obj=%p)", *obj);
assert(fromSpaceContains(*obj));
clazz = (*obj)->clazz;
if (isForward(clazz)) {
// LOG_SCAV("forwarding %p @ %p to %p", *obj, obj, (void *)((uintptr_t)clazz & ~0x1));
*obj = (Object *)getForward(clazz);
return;
}
fromObj = *obj;
if (clazz == NULL) {
// LOG_SCAV("scavangeReference %p has a NULL class object", fromObj);
assert(!"implemented");
toObj = NULL;
} else {
toObj = transportObject(fromObj);
}
setForward(toObj, fromObj);
*obj = (Object *)toObj;
}
/*
* Generic object scavenging.
*/
static void scavengeObject(Object *obj)
{
ClassObject *clazz;
assert(obj != NULL);
assert(obj->clazz != NULL);
assert(!((uintptr_t)obj->clazz & 0x1));
clazz = obj->clazz;
if (clazz == gDvm.classJavaLangClass) {
scavengeClassObject((ClassObject *)obj);
} else if (IS_CLASS_FLAG_SET(clazz, CLASS_ISARRAY)) {
scavengeArrayObject((ArrayObject *)obj);
} else if (IS_CLASS_FLAG_SET(clazz, CLASS_ISREFERENCE)) {
scavengeReferenceObject(obj);
} else {
scavengeDataObject(obj);
}
}
/*
* External root scavenging routines.
*/
static void pinHashTableEntries(HashTable *table)
{
HashEntry *entry;
void *obj;
int i;
LOG_PIN(">>> pinHashTableEntries(table=%p)", table);
if (table == NULL) {
return;
}
dvmHashTableLock(table);
for (i = 0; i < table->tableSize; ++i) {
entry = &table->pEntries[i];
obj = entry->data;
if (obj == NULL || obj == HASH_TOMBSTONE) {
continue;
}
pinObject(entry->data);
}
dvmHashTableUnlock(table);
LOG_PIN("<<< pinHashTableEntries(table=%p)", table);
}
static void pinPrimitiveClasses(void)
{
size_t length;
size_t i;
length = ARRAYSIZE(gDvm.primitiveClass);
for (i = 0; i < length; i++) {
if (gDvm.primitiveClass[i] != NULL) {
pinObject((Object *)gDvm.primitiveClass[i]);
}
}
}
/*
* Scavenge interned strings. Permanent interned strings will have
* been pinned and are therefore ignored. Non-permanent strings that
* have been forwarded are snapped. All other entries are removed.
*/
static void scavengeInternedStrings(void)
{
HashTable *table;
HashEntry *entry;
Object *obj;
int i;
table = gDvm.internedStrings;
if (table == NULL) {
return;
}
dvmHashTableLock(table);
for (i = 0; i < table->tableSize; ++i) {
entry = &table->pEntries[i];
obj = (Object *)entry->data;
if (obj == NULL || obj == HASH_TOMBSTONE) {
continue;
} else if (!isPermanentString((StringObject *)obj)) {
// LOG_SCAV("entry->data=%p", entry->data);
LOG_SCAV(">>> string obj=%p", entry->data);
/* TODO(cshapiro): detach white string objects */
scavengeReference((Object **)(void *)&entry->data);
LOG_SCAV("<<< string obj=%p", entry->data);
}
}
dvmHashTableUnlock(table);
}
static void pinInternedStrings(void)
{
HashTable *table;
HashEntry *entry;
Object *obj;
int i;
table = gDvm.internedStrings;
if (table == NULL) {
return;
}
dvmHashTableLock(table);
for (i = 0; i < table->tableSize; ++i) {
entry = &table->pEntries[i];
obj = (Object *)entry->data;
if (obj == NULL || obj == HASH_TOMBSTONE) {
continue;
} else if (isPermanentString((StringObject *)obj)) {
obj = (Object *)getPermanentString((StringObject*)obj);
LOG_PROM(">>> pin string obj=%p", obj);
pinObject(obj);
LOG_PROM("<<< pin string obj=%p", obj);
}
}
dvmHashTableUnlock(table);
}
/*
* At present, reference tables contain references that must not be
* moved by the collector. Instead of scavenging each reference in
* the table we pin each referenced object.
*/
static void pinReferenceTable(const ReferenceTable *table)
{
Object **entry;
assert(table != NULL);
assert(table->table != NULL);
assert(table->nextEntry != NULL);
for (entry = table->table; entry < table->nextEntry; ++entry) {
assert(entry != NULL);
assert(!isForward(*entry));
pinObject(*entry);
}
}
static void scavengeLargeHeapRefTable(LargeHeapRefTable *table)
{
for (; table != NULL; table = table->next) {
Object **ref = table->refs.table;
for (; ref < table->refs.nextEntry; ++ref) {
scavengeReference(ref);
}
}
}
/* This code was copied from Thread.c */
static void scavengeThreadStack(Thread *thread)
{
const u4 *framePtr;
#if WITH_EXTRA_GC_CHECKS > 1
bool first = true;
#endif
framePtr = (const u4 *)thread->curFrame;
while (framePtr != NULL) {
const StackSaveArea *saveArea;
const Method *method;
saveArea = SAVEAREA_FROM_FP(framePtr);
method = saveArea->method;
if (method != NULL && !dvmIsNativeMethod(method)) {
#ifdef COUNT_PRECISE_METHODS
/* the GC is running, so no lock required */
if (dvmPointerSetAddEntry(gDvm.preciseMethods, method))
LOG_SCAV("PGC: added %s.%s %p\n",
method->clazz->descriptor, method->name, method);
#endif
#if WITH_EXTRA_GC_CHECKS > 1
/*
* May also want to enable the memset() in the "invokeMethod"
* goto target in the portable interpreter. That sets the stack
* to a pattern that makes referring to uninitialized data
* very obvious.
*/
if (first) {
/*
* First frame, isn't native, check the "alternate" saved PC
* as a sanity check.
*
* It seems like we could check the second frame if the first
* is native, since the PCs should be the same. It turns out
* this doesn't always work. The problem is that we could
* have calls in the sequence:
* interp method #2
* native method
* interp method #1
*
* and then GC while in the native method after returning
* from interp method #2. The currentPc on the stack is
* for interp method #1, but thread->currentPc2 is still
* set for the last thing interp method #2 did.
*
* This can also happen in normal execution:
* - sget-object on not-yet-loaded class
* - class init updates currentPc2
* - static field init is handled by parsing annotations;
* static String init requires creation of a String object,
* which can cause a GC
*
* Essentially, any pattern that involves executing
* interpreted code and then causes an allocation without
* executing instructions in the original method will hit
* this. These are rare enough that the test still has
* some value.
*/
if (saveArea->xtra.currentPc != thread->currentPc2) {
LOGW("PGC: savedPC(%p) != current PC(%p), %s.%s ins=%p\n",
saveArea->xtra.currentPc, thread->currentPc2,
method->clazz->descriptor, method->name, method->insns);
if (saveArea->xtra.currentPc != NULL)
LOGE(" pc inst = 0x%04x\n", *saveArea->xtra.currentPc);
if (thread->currentPc2 != NULL)
LOGE(" pc2 inst = 0x%04x\n", *thread->currentPc2);
dvmDumpThread(thread, false);
}
} else {
/*
* It's unusual, but not impossible, for a non-first frame
* to be at something other than a method invocation. For
* example, if we do a new-instance on a nonexistent class,
* we'll have a lot of class loader activity on the stack
* above the frame with the "new" operation. Could also
* happen while we initialize a Throwable when an instruction
* fails.
*
* So there's not much we can do here to verify the PC,
* except to verify that it's a GC point.
*/
}
assert(saveArea->xtra.currentPc != NULL);
#endif
const RegisterMap* pMap;
const u1* regVector;
int i;
Method* nonConstMethod = (Method*) method; // quiet gcc
pMap = dvmGetExpandedRegisterMap(nonConstMethod);
//LOG_SCAV("PGC: %s.%s\n", method->clazz->descriptor, method->name);
if (pMap != NULL) {
/* found map, get registers for this address */
int addr = saveArea->xtra.currentPc - method->insns;
regVector = dvmRegisterMapGetLine(pMap, addr);
/*
if (regVector == NULL) {
LOG_SCAV("PGC: map but no entry for %s.%s addr=0x%04x\n",
method->clazz->descriptor, method->name, addr);
} else {
LOG_SCAV("PGC: found map for %s.%s 0x%04x (t=%d)\n",
method->clazz->descriptor, method->name, addr,
thread->threadId);
}
*/
} else {
/*
* No map found. If precise GC is disabled this is
* expected -- we don't create pointers to the map data even
* if it's present -- but if it's enabled it means we're
* unexpectedly falling back on a conservative scan, so it's
* worth yelling a little.
*/
if (gDvm.preciseGc) {
LOG_SCAV("PGC: no map for %s.%s\n", method->clazz->descriptor, method->name);
}
regVector = NULL;
}
if (regVector == NULL) {
/*
* There are no roots to scavenge. Skip over the entire frame.
*/
framePtr += method->registersSize;
} else {
/*
* Precise scan. v0 is at the lowest address on the
* interpreted stack, and is the first bit in the register
* vector, so we can walk through the register map and
* memory in the same direction.
*
* A '1' bit indicates a live reference.
*/
u2 bits = 1 << 1;
for (i = method->registersSize - 1; i >= 0; i--) {
u4 rval = *framePtr;
bits >>= 1;
if (bits == 1) {
/* set bit 9 so we can tell when we're empty */
bits = *regVector++ | 0x0100;
}
if (rval != 0 && (bits & 0x01) != 0) {
/*
* Non-null, register marked as live reference. This
* should always be a valid object.
*/
#if WITH_EXTRA_GC_CHECKS > 0
if ((rval & 0x3) != 0 || !dvmIsValidObject((Object*) rval)) {
/* this is very bad */
LOGE("PGC: invalid ref in reg %d: 0x%08x\n",
method->registersSize-1 - i, rval);
} else
#endif
{
// LOG_SCAV("stack reference %u@%p", *framePtr, framePtr);
/* dvmMarkObjectNonNull((Object *)rval); */
scavengeReference((Object **) framePtr);
}
} else {
/*
* Null or non-reference, do nothing at all.
*/
#if WITH_EXTRA_GC_CHECKS > 1
if (dvmIsValidObject((Object*) rval)) {
/* this is normal, but we feel chatty */
LOGD("PGC: ignoring valid ref in reg %d: 0x%08x\n",
method->registersSize-1 - i, rval);
}
#endif
}
++framePtr;
}
dvmReleaseRegisterMapLine(pMap, regVector);
}
}
/* else this is a break frame and there is nothing to gray, or
* this is a native method and the registers are just the "ins",
* copied from various registers in the caller's set.
*/
#if WITH_EXTRA_GC_CHECKS > 1
first = false;
#endif
/* Don't fall into an infinite loop if things get corrupted.
*/
assert((uintptr_t)saveArea->prevFrame > (uintptr_t)framePtr ||
saveArea->prevFrame == NULL);
framePtr = saveArea->prevFrame;
}
}
static void scavengeThread(Thread *thread)
{
// LOG_SCAV("scavengeThread(thread=%p)", thread);
// LOG_SCAV("Scavenging threadObj=%p", thread->threadObj);
scavengeReference(&thread->threadObj);
// LOG_SCAV("Scavenging exception=%p", thread->exception);
scavengeReference(&thread->exception);
scavengeThreadStack(thread);
}
static void scavengeThreadList(void)
{
Thread *thread;
dvmLockThreadList(dvmThreadSelf());
thread = gDvm.threadList;
while (thread) {
scavengeThread(thread);
thread = thread->next;
}
dvmUnlockThreadList();
}
static void pinThreadStack(const Thread *thread)
{
const u4 *framePtr;
const StackSaveArea *saveArea;
Method *method;
const char *shorty;
Object *obj;
int i;
saveArea = NULL;
framePtr = (const u4 *)thread->curFrame;
for (; framePtr != NULL; framePtr = saveArea->prevFrame) {
saveArea = SAVEAREA_FROM_FP(framePtr);
method = (Method *)saveArea->method;
if (method != NULL && dvmIsNativeMethod(method)) {
/*
* This is native method, pin its arguments.
*
* For purposes of graying references, we don't need to do
* anything here, because all of the native "ins" were copied
* from registers in the caller's stack frame and won't be
* changed (an interpreted method can freely use registers
* with parameters like any other register, but natives don't
* work that way).
*
* However, we need to ensure that references visible to
* native methods don't move around. We can do a precise scan
* of the arguments by examining the method signature.
*/
LOG_PIN("+++ native scan %s.%s\n",
method->clazz->descriptor, method->name);
assert(method->registersSize == method->insSize);
if (!dvmIsStaticMethod(method)) {
/* grab the "this" pointer */
obj = (Object *)*framePtr++;
if (obj == NULL) {
/*
* This can happen for the "fake" entry frame inserted
* for threads created outside the VM. There's no actual
* call so there's no object. If we changed the fake
* entry method to be declared "static" then this
* situation should never occur.
*/
} else {
assert(dvmIsValidObject(obj));
pinObject(obj);
}
}
shorty = method->shorty+1; // skip return value
for (i = method->registersSize - 1; i >= 0; i--, framePtr++) {
switch (*shorty++) {
case 'L':
obj = (Object *)*framePtr;
if (obj != NULL) {
assert(dvmIsValidObject(obj));
pinObject(obj);
}
break;
case 'D':
case 'J':
framePtr++;
break;
default:
/* 32-bit non-reference value */
obj = (Object *)*framePtr; // debug, remove
if (dvmIsValidObject(obj)) { // debug, remove
/* if we see a lot of these, our scan might be off */
LOG_PIN("+++ did NOT pin obj %p\n", obj);
}
break;
}
}
} else if (method != NULL && !dvmIsNativeMethod(method)) {
const RegisterMap* pMap = dvmGetExpandedRegisterMap(method);
const u1* regVector = NULL;
LOGI("conservative : %s.%s\n", method->clazz->descriptor, method->name);
if (pMap != NULL) {
int addr = saveArea->xtra.currentPc - method->insns;
regVector = dvmRegisterMapGetLine(pMap, addr);
}
if (regVector == NULL) {
/*
* No register info for this frame, conservatively pin.
*/
for (i = 0; i < method->registersSize; ++i) {
u4 regValue = framePtr[i];
if (regValue != 0 && (regValue & 0x3) == 0 && dvmIsValidObject((Object *)regValue)) {
pinObject((Object *)regValue);
}
}
}
}
/*
* Don't fall into an infinite loop if things get corrupted.
*/
assert((uintptr_t)saveArea->prevFrame > (uintptr_t)framePtr ||
saveArea->prevFrame == NULL);
}
}
static void pinThread(const Thread *thread)
{
assert(thread != NULL);
LOG_PIN("pinThread(thread=%p)", thread);
LOG_PIN("Pin native method arguments");
pinThreadStack(thread);
LOG_PIN("Pin internalLocalRefTable");
pinReferenceTable(&thread->internalLocalRefTable);
LOG_PIN("Pin jniLocalRefTable");
pinReferenceTable(&thread->jniLocalRefTable);
/* Can the check be pushed into the promote routine? */
if (thread->jniMonitorRefTable.table) {
LOG_PIN("Pin jniMonitorRefTable");
pinReferenceTable(&thread->jniMonitorRefTable);
}
}
static void pinThreadList(void)
{
Thread *thread;
dvmLockThreadList(dvmThreadSelf());
thread = gDvm.threadList;
while (thread) {
pinThread(thread);
thread = thread->next;
}
dvmUnlockThreadList();
}
/*
* Heap block scavenging.
*/
/*
* Scavenge objects in the current block. Scavenging terminates when
* the pointer reaches the highest address in the block or when a run
* of zero words that continues to the highest address is reached.
*/
static void scavengeBlock(HeapSource *heapSource, size_t block)
{
u1 *cursor;
u1 *end;
size_t size;
LOG_SCAV("scavengeBlock(heapSource=%p,block=%zu)", heapSource, block);
assert(heapSource != NULL);
assert(block < heapSource->totalBlocks);
assert(heapSource->blockSpace[block] == BLOCK_TO_SPACE);
cursor = blockToAddress(heapSource, block);
end = cursor + BLOCK_SIZE;
LOG_SCAV("scavengeBlock start=%p, end=%p", cursor, end);
/* Parse and scavenge the current block. */
size = 0;
while (cursor < end) {
u4 word = *(u4 *)cursor;
if (word != 0) {
scavengeObject((Object *)cursor);
size = objectSize((Object *)cursor);
size = alignUp(size, ALLOC_ALIGNMENT);
cursor += size;
} else {
/* Check for padding. */
while (*(u4 *)cursor == 0) {
cursor += 4;
if (cursor == end) break;
}
/* Punt if something went wrong. */
assert(cursor == end);
}
}
}
static size_t objectSize(const Object *obj)
{
size_t size;
assert(obj != NULL);
assert(obj->clazz != NULL);
if (obj->clazz == gDvm.classJavaLangClass) {
size = dvmClassObjectSize((ClassObject *)obj);
} else if (IS_CLASS_FLAG_SET(obj->clazz, CLASS_ISARRAY)) {
size = dvmArrayObjectSize((ArrayObject *)obj);
} else {
assert(obj->clazz->objectSize != 0);
size = obj->clazz->objectSize;
}
if (LW_HASH_STATE(obj->lock) == LW_HASH_STATE_HASHED_AND_MOVED) {
size += sizeof(u4);
}
return size;
}
static void verifyBlock(HeapSource *heapSource, size_t block)
{
u1 *cursor;
u1 *end;
size_t size;
// LOG_VER("verifyBlock(heapSource=%p,block=%zu)", heapSource, block);
assert(heapSource != NULL);
assert(block < heapSource->totalBlocks);
assert(heapSource->blockSpace[block] == BLOCK_TO_SPACE);
cursor = blockToAddress(heapSource, block);
end = cursor + BLOCK_SIZE;
// LOG_VER("verifyBlock start=%p, end=%p", cursor, end);
/* Parse and scavenge the current block. */
size = 0;
while (cursor < end) {
u4 word = *(u4 *)cursor;
if (word != 0) {
dvmVerifyObject((Object *)cursor);
size = objectSize((Object *)cursor);
size = alignUp(size, ALLOC_ALIGNMENT);
cursor += size;
} else {
/* Check for padding. */
while (*(unsigned long *)cursor == 0) {
cursor += 4;
if (cursor == end) break;
}
/* Punt if something went wrong. */
assert(cursor == end);
}
}
}
static void describeBlockQueue(const HeapSource *heapSource)
{
size_t block, count;
char space;
block = heapSource->queueHead;
count = 0;
LOG_SCAV(">>> describeBlockQueue(heapSource=%p)", heapSource);
/* Count the number of blocks enqueued. */
while (block != QUEUE_TAIL) {
block = heapSource->blockQueue[block];
++count;
}
LOG_SCAV("blockQueue %zu elements, enqueued %zu",
count, heapSource->queueSize);
block = heapSource->queueHead;
while (block != QUEUE_TAIL) {
space = heapSource->blockSpace[block];
LOG_SCAV("block=%zu@%p,space=%zu", block, blockToAddress(heapSource,block), space);
block = heapSource->blockQueue[block];
}
LOG_SCAV("<<< describeBlockQueue(heapSource=%p)", heapSource);
}
/*
* Blackens promoted objects.
*/
static void scavengeBlockQueue(void)
{
HeapSource *heapSource;
size_t block;
LOG_SCAV(">>> scavengeBlockQueue()");
heapSource = gDvm.gcHeap->heapSource;
describeBlockQueue(heapSource);
while (heapSource->queueHead != QUEUE_TAIL) {
block = heapSource->queueHead;
LOG_SCAV("Dequeueing block %zu\n", block);
scavengeBlock(heapSource, block);
heapSource->queueHead = heapSource->blockQueue[block];
LOG_SCAV("New queue head is %zu\n", heapSource->queueHead);
}
LOG_SCAV("<<< scavengeBlockQueue()");
}
/*
* Scan the block list and verify all blocks that are marked as being
* in new space. This should be parametrized so we can invoke this
* routine outside of the context of a collection.
*/
static void verifyNewSpace(void)
{
HeapSource *heapSource;
size_t i;
size_t c0, c1, c2, c7;
c0 = c1 = c2 = c7 = 0;
heapSource = gDvm.gcHeap->heapSource;
for (i = 0; i < heapSource->totalBlocks; ++i) {
switch (heapSource->blockSpace[i]) {
case BLOCK_FREE: ++c0; break;
case BLOCK_TO_SPACE: ++c1; break;
case BLOCK_FROM_SPACE: ++c2; break;
case BLOCK_CONTINUED: ++c7; break;
default: assert(!"reached");
}
}
LOG_VER("Block Demographics: "
"Free=%zu,ToSpace=%zu,FromSpace=%zu,Continued=%zu",
c0, c1, c2, c7);
for (i = 0; i < heapSource->totalBlocks; ++i) {
if (heapSource->blockSpace[i] != BLOCK_TO_SPACE) {
continue;
}
verifyBlock(heapSource, i);
}
}
static void scavengeGlobals(void)
{
scavengeReference((Object **)(void *)&gDvm.classJavaLangClass);
scavengeReference((Object **)(void *)&gDvm.classJavaLangClassArray);
scavengeReference((Object **)(void *)&gDvm.classJavaLangError);
scavengeReference((Object **)(void *)&gDvm.classJavaLangObject);
scavengeReference((Object **)(void *)&gDvm.classJavaLangObjectArray);
scavengeReference((Object **)(void *)&gDvm.classJavaLangRuntimeException);
scavengeReference((Object **)(void *)&gDvm.classJavaLangString);
scavengeReference((Object **)(void *)&gDvm.classJavaLangThread);
scavengeReference((Object **)(void *)&gDvm.classJavaLangVMThread);
scavengeReference((Object **)(void *)&gDvm.classJavaLangThreadGroup);
scavengeReference((Object **)(void *)&gDvm.classJavaLangThrowable);
scavengeReference((Object **)(void *)&gDvm.classJavaLangStackTraceElement);
scavengeReference((Object **)(void *)&gDvm.classJavaLangStackTraceElementArray);
scavengeReference((Object **)(void *)&gDvm.classJavaLangAnnotationAnnotationArray);
scavengeReference((Object **)(void *)&gDvm.classJavaLangAnnotationAnnotationArrayArray);
scavengeReference((Object **)(void *)&gDvm.classJavaLangReflectAccessibleObject);
scavengeReference((Object **)(void *)&gDvm.classJavaLangReflectConstructor);
scavengeReference((Object **)(void *)&gDvm.classJavaLangReflectConstructorArray);
scavengeReference((Object **)(void *)&gDvm.classJavaLangReflectField);
scavengeReference((Object **)(void *)&gDvm.classJavaLangReflectFieldArray);
scavengeReference((Object **)(void *)&gDvm.classJavaLangReflectMethod);
scavengeReference((Object **)(void *)&gDvm.classJavaLangReflectMethodArray);
scavengeReference((Object **)(void *)&gDvm.classJavaLangReflectProxy);
scavengeReference((Object **)(void *)&gDvm.classJavaLangExceptionInInitializerError);
scavengeReference((Object **)(void *)&gDvm.classJavaLangRefReference);
scavengeReference((Object **)(void *)&gDvm.classJavaNioReadWriteDirectByteBuffer);
scavengeReference((Object **)(void *)&gDvm.classJavaSecurityAccessController);
scavengeReference((Object **)(void *)&gDvm.classOrgApacheHarmonyLangAnnotationAnnotationFactory);
scavengeReference((Object **)(void *)&gDvm.classOrgApacheHarmonyLangAnnotationAnnotationMember);
scavengeReference((Object **)(void *)&gDvm.classOrgApacheHarmonyLangAnnotationAnnotationMemberArray);
scavengeReference((Object **)(void *)&gDvm.classOrgApacheHarmonyNioInternalDirectBuffer);
scavengeReference((Object **)(void *)&gDvm.classArrayBoolean);
scavengeReference((Object **)(void *)&gDvm.classArrayChar);
scavengeReference((Object **)(void *)&gDvm.classArrayFloat);
scavengeReference((Object **)(void *)&gDvm.classArrayDouble);
scavengeReference((Object **)(void *)&gDvm.classArrayByte);
scavengeReference((Object **)(void *)&gDvm.classArrayShort);
scavengeReference((Object **)(void *)&gDvm.classArrayInt);
scavengeReference((Object **)(void *)&gDvm.classArrayLong);
}
void describeHeap(void)
{
HeapSource *heapSource;
heapSource = gDvm.gcHeap->heapSource;
describeBlocks(heapSource);
}
/*
* The collection interface. Collection has a few distinct phases.
* The first is flipping AKA condemning AKA whitening the heap. The
* second is to promote all objects which are pointed to by pinned or
* ambiguous references. The third phase is tracing from the stacks,
* registers and various globals. Lastly, a verification of the heap
* is performed. The last phase should be optional.
*/
void dvmScavengeRoots(void) /* Needs a new name badly */
{
GcHeap *gcHeap;
{
size_t alloc, unused, total;
room(&alloc, &unused, &total);
LOG_SCAV("BEFORE GC: %zu alloc, %zu free, %zu total.",
alloc, unused, total);
}
gcHeap = gDvm.gcHeap;
dvmHeapSourceFlip();
/*
* Promote blocks with stationary objects.
*/
pinThreadList();
pinReferenceTable(&gDvm.jniGlobalRefTable);
pinReferenceTable(&gDvm.jniPinRefTable);
pinHashTableEntries(gDvm.loadedClasses);
pinHashTableEntries(gDvm.dbgRegistry);
pinPrimitiveClasses();
pinInternedStrings();
// describeBlocks(gcHeap->heapSource);
/*
* Create first, open new-space page right here.
*/
/* Reset allocation to an unallocated block. */
gDvm.gcHeap->heapSource->allocPtr = allocateBlocks(gDvm.gcHeap->heapSource, 1);
gDvm.gcHeap->heapSource->allocLimit = gDvm.gcHeap->heapSource->allocPtr + BLOCK_SIZE;
/*
* Hack: promote the empty block allocated above. If the
* promotions that occurred above did not actually gray any
* objects, the block queue may be empty. We must force a
* promotion to be safe.
*/
promoteBlockByAddr(gDvm.gcHeap->heapSource, gDvm.gcHeap->heapSource->allocPtr);
/*
* Scavenge blocks and relocate movable objects.
*/
LOG_SCAV("Scavenging gDvm.threadList");
scavengeThreadList();
LOG_SCAV("Scavenging gDvm.gcHeap->referenceOperations");
scavengeLargeHeapRefTable(gcHeap->referenceOperations);
LOG_SCAV("Scavenging gDvm.gcHeap->pendingFinalizationRefs");
scavengeLargeHeapRefTable(gcHeap->pendingFinalizationRefs);
LOG_SCAV("Scavenging random global stuff");
scavengeReference(&gDvm.outOfMemoryObj);
scavengeReference(&gDvm.internalErrorObj);
scavengeReference(&gDvm.noClassDefFoundErrorObj);
// LOG_SCAV("Scavenging gDvm.internedString");
scavengeInternedStrings();
LOG_SCAV("Root scavenge has completed.");
scavengeBlockQueue();
LOG_SCAV("Re-snap global class pointers.");
scavengeGlobals();
LOG_SCAV("New space scavenge has completed.");
/*
* Process reference objects in strength order.
*/
LOG_REF("Processing soft references...");
preserveSoftReferences(&gDvm.gcHeap->softReferences);
clearWhiteReferences(&gDvm.gcHeap->softReferences);
LOG_REF("Processing weak references...");
clearWhiteReferences(&gDvm.gcHeap->weakReferences);
LOG_REF("Finding finalizations...");
processFinalizableReferences();
LOG_REF("Processing f-reachable soft references...");
clearWhiteReferences(&gDvm.gcHeap->softReferences);
LOG_REF("Processing f-reachable weak references...");
clearWhiteReferences(&gDvm.gcHeap->weakReferences);
LOG_REF("Processing phantom references...");
clearWhiteReferences(&gDvm.gcHeap->phantomReferences);
/*
* Verify the stack and heap.
*/
dvmVerifyRoots();
verifyNewSpace();
//describeBlocks(gcHeap->heapSource);
clearFromSpace(gcHeap->heapSource);
{
size_t alloc, rem, total;
room(&alloc, &rem, &total);
LOG_SCAV("AFTER GC: %zu alloc, %zu free, %zu total.", alloc, rem, total);
}
}
/*
* Interface compatibility routines.
*/
void dvmClearWhiteRefs(Object **list)
{
/* do nothing */
assert(*list == NULL);
}
void dvmHandleSoftRefs(Object **list)
{
/* do nothing */
assert(*list == NULL);
}
bool dvmHeapBeginMarkStep(GcMode mode)
{
/* do nothing */
return true;
}
void dvmHeapFinishMarkStep(void)
{
/* do nothing */
}
void dvmHeapMarkRootSet(void)
{
/* do nothing */
}
void dvmHeapScanMarkedObjects(void)
{
dvmScavengeRoots();
}
void dvmHeapScheduleFinalizations(void)
{
/* do nothing */
}
void dvmHeapSweepUnmarkedObjects(GcMode mode, int *numFreed, size_t *sizeFreed)
{
*numFreed = 0;
*sizeFreed = 0;
/* do nothing */
}
void dvmMarkObjectNonNull(const Object *obj)
{
assert(!"implemented");
}
void dvmMarkDirtyObjects(void)
{
assert(!"implemented");
}
void dvmHeapSourceThreadShutdown(void)
{
/* do nothing */
}