If Ashmem cache fails pinCache, do not reallocate.

src/ports/SkAshmemImageCache.cpp

Index: src/ports/SkAshmemImageCache.cpp
diff --git a/src/ports/SkAshmemImageCache.cpp b/src/ports/SkAshmemImageCache.cpp
index a85542271df733e5c2a421f62e4ef9c69a38008e..b7c6c7058b7d23f96c87b5bed293a6f985a8f4ca 100644
--- a/src/ports/SkAshmemImageCache.cpp
+++ b/src/ports/SkAshmemImageCache.cpp
@@ -41,11 +41,26 @@ static size_t roundToPageSize(size_t size) {
 }
 
 void* SkAshmemImageCache::allocAndPinCache(size_t bytes, intptr_t* ID) {
-    AshmemRec rec;
-    rec.fSize = roundToPageSize(bytes);
+    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);

[reed1, 2013/03/04 21:05:35]

What is the return value for ashmem_pin_region that we are ignoring?

[scroggo, 2013/03/04 21:10:47]

ASHMEM_WAS_PURGED or ASHMEM_NOT_PURGED. In this case, we already discovered that
the memory was purged (which is why we call allocAndPinCache again), so we do
not care about the return value (same down below, for the newly allocated memory
in this same function).

+        (void) ashmem_pin_region(pRec->fFD, 0, 0);
+#ifdef SK_DEBUG
+        pRec->fPinned = true;
+#endif
+        return pRec->fAddr;
+    }
+
+    AshmemRec rec;
+    rec.fSize = roundToPageSize(bytes);
+
     rec.fFD = ashmem_create_region(NULL, rec.fSize);
     if (-1 == rec.fFD) {
         SkDebugf("ashmem_create_region failed\n");
@@ -70,7 +85,6 @@ void* SkAshmemImageCache::allocAndPinCache(size_t bytes, intptr_t* ID) {
     // 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);
@@ -89,8 +103,6 @@ void* SkAshmemImageCache::pinCache(intptr_t ID) {
 #endif
         return rec->fAddr;
     }
-    // Purged. Remove the associated AshmemRec:
-    this->removeRec(rec);
     ashmem_unpin_region(fd, 0, 0);
     return NULL;
 }
@@ -107,16 +119,10 @@ void SkAshmemImageCache::releaseCache(intptr_t ID) {
 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);