If Ashmem cache fails pinCache, do not reallocate.

src/ports/SkAshmemImageCache.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkAshmemImageCache.h"
 #include "SkThread.h"
 
@@ skipping 23 matching lines @@
 #endif
 
 // ashmem likes lengths on page boundaries.
 static size_t roundToPageSize(size_t size) {
     const size_t mask = getpagesize() - 1;
     size_t newSize = (size + mask) & ~mask;
     return newSize;
 }
 
 void* SkAshmemImageCache::allocAndPinCache(size_t bytes, intptr_t* ID) {
+    SkASSERT(ID != NULL);
+
+    SkAutoMutexAcquire ac(&gAshmemMutex);
+
+    if (*ID != SkImageCache::UNINITIALIZED_ID) {
+        // This rec was previously allocated, but pinCache subsequently
+        // failed.
+        AshmemRec* pRec = reinterpret_cast<AshmemRec*>(*ID);
+        SkASSERT(roundToPageSize(bytes) == pRec->fSize);
+        SkASSERT(pRec->fFD != -1);
+        (void) ashmem_pin_region(pRec->fFD, 0, 0);
+#ifdef SK_DEBUG
+        pRec->fPinned = true;
+#endif
+        return pRec->fAddr;
+    }
+
     AshmemRec rec;
     rec.fSize = roundToPageSize(bytes);
 
-    SkAutoMutexAcquire ac(&gAshmemMutex);
-
     rec.fFD = ashmem_create_region(NULL, rec.fSize);
     if (-1 == rec.fFD) {
         SkDebugf("ashmem_create_region failed\n");
         return NULL;
     }
     int err = ashmem_set_prot_region(rec.fFD, PROT_READ | PROT_WRITE);
     if (err != 0) {
         SkDebugf("ashmem_set_prot_region failed\n");
         close(rec.fFD);
         return NULL;
     }
     rec.fAddr = mmap(NULL, rec.fSize, PROT_READ | PROT_WRITE, MAP_PRIVATE, rec.fFD, 0);
     if (-1 == (long) rec.fAddr) {
         SkDebugf("mmap failed\n");
         close(rec.fFD);
         return NULL;
     }
     (void) ashmem_pin_region(rec.fFD, 0, 0);
 #ifdef SK_DEBUG
     rec.fPinned = true;
 #endif
     // In release mode, we do not keep a pointer to this object. It will be destroyed
     // either when pinCache returns NULL or when throwAwayCache is called.
     AshmemRec* pRec = SkNEW_ARGS(AshmemRec, (rec));
-    SkASSERT(ID != NULL);
     *ID = reinterpret_cast<intptr_t>(pRec);
 #ifdef SK_DEBUG
     this->appendRec(pRec);
 #endif
     return rec.fAddr;
 }
 
 void* SkAshmemImageCache::pinCache(intptr_t ID) {
     SkAutoMutexAcquire ac(&gAshmemMutex);
     AshmemRec* rec = reinterpret_cast<AshmemRec*>(ID);
     const int fd = rec->fFD;
     int pin = ashmem_pin_region(fd, 0, 0);
     if (ASHMEM_NOT_PURGED == pin) {
 #ifdef SK_DEBUG
         rec->fPinned = true;
 #endif
         return rec->fAddr;
     }
-    // Purged. Remove the associated AshmemRec:
-    this->removeRec(rec);
     ashmem_unpin_region(fd, 0, 0);
     return NULL;
 }
 
 void SkAshmemImageCache::releaseCache(intptr_t ID) {
     SkAutoMutexAcquire ac(&gAshmemMutex);
     AshmemRec* rec = reinterpret_cast<AshmemRec*>(ID);
     ashmem_unpin_region(rec->fFD, 0, 0);
 #ifdef SK_DEBUG
     rec->fPinned = false;
 #endif
 }
 
 void SkAshmemImageCache::throwAwayCache(intptr_t ID) {
     SkAutoMutexAcquire ac(&gAshmemMutex);
     AshmemRec* rec = reinterpret_cast<AshmemRec*>(ID);
-#ifdef SK_DEBUG
-    SkASSERT(!rec->fPinned);
-#endif
-    this->removeRec(rec);
-}
-
-void SkAshmemImageCache::removeRec(SkAshmemImageCache::AshmemRec* rec) {
     munmap(rec->fAddr, rec->fSize);
     close(rec->fFD);
 #ifdef SK_DEBUG
+    SkASSERT(!rec->fPinned);
     int index = this->findRec(rec);
     SkASSERT(index >= 0);
     fRecs.remove(index);
 #endif
     SkDELETE(rec);
 }
 
 #ifdef SK_DEBUG
 void SkAshmemImageCache::appendRec(SkAshmemImageCache::AshmemRec* rec) {
     int index = this->findRec(rec);
@@ skipping 16 matching lines @@
     SkAutoMutexAcquire ac(&gAshmemMutex);
     AshmemRec* rec = reinterpret_cast<AshmemRec*>(ID);
     int index = this->findRec(rec);
     if (index < 0) {
         return SkImageCache::kThrownAway_CacheStatus;
     }
     return rec->fPinned ? SkImageCache::kPinned_CacheStatus
                         : SkImageCache::kUnpinned_CacheStatus;
 }
 #endif