Add partitionsOutOfMemoryUsingXXX to know Blink memory usage from OOM crash reports

Source/wtf/PartitionAlloc.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 298 matching lines @@
     uintptr_t invertedSelf;
 
     static int gInitializedLock;
     static bool gInitialized;
     // gSeedPage is used as a sentinel to indicate that there is no page
     // in the active page list. We can use nullptr, but in that case we need
     // to add a null-check branch to the hot allocation path. We want to avoid
     // that.
     static PartitionPage gSeedPage;
     static PartitionBucket gPagedBucket;
+    // gMemoryUsageReportFunction is used to know how much memory Blink
+    // has already allocated when OOM occurrs.
+    // Currently Partitions registers this function.
+    static size_t (*gMemoryUsageReportFunction)();

[haraken, 2015/09/04 05:22:45]

Instead of exporting gMemoryUsageReportFunction, how about exporting
oomHandlingFunction? Then you can define oomHandlingFunction outside
PartitionAlloc and thus can do whatever you want. It would be more flexible.

[tasak, 2015/09/04 06:12:06]

Done.

 };
 
 // Never instantiate a PartitionRoot directly, instead use PartitionAlloc.
 struct PartitionRoot : public PartitionRootBase {
     // The PartitionAlloc templated class ensures the following is correct.
     ALWAYS_INLINE PartitionBucket* buckets() { return reinterpret_cast<PartitionBucket*>(this + 1); }
     ALWAYS_INLINE const PartitionBucket* buckets() const { return reinterpret_cast<const PartitionBucket*>(this + 1); }
 };
 
 // Never instantiate a PartitionRootGeneric directly, instead use PartitionAllocatorGeneric.
@@ skipping 47 matching lines @@
 // partitionDumpStatsGeneric for using the memory statistics.
 class WTF_EXPORT PartitionStatsDumper {
 public:
     // Called to dump total memory used by partition, once per partition.
     virtual void partitionDumpTotals(const char* partitionName, const PartitionMemoryStats*) = 0;
 
     // Called to dump stats about buckets, for each bucket.
     virtual void partitionsDumpBucketStats(const char* partitionName, const PartitionBucketMemoryStats*) = 0;
 };
 
+WTF_EXPORT void partitionAllocGlobalInit(size_t (*memoryUsageReportFunc)());
 WTF_EXPORT void partitionAllocInit(PartitionRoot*, size_t numBuckets, size_t maxAllocation);
 WTF_EXPORT bool partitionAllocShutdown(PartitionRoot*);
 WTF_EXPORT void partitionAllocGenericInit(PartitionRootGeneric*);
 WTF_EXPORT bool partitionAllocGenericShutdown(PartitionRootGeneric*);
 
 enum PartitionPurgeFlags {
     // Decommitting the ring list of empty pages is reasonably fast.
     PartitionPurgeDecommitEmptyPages = 1 << 0,
     // Discarding unused system pages is slower, because it involves walking all
     // freelists in all active partition pages of all buckets >= system page
@@ skipping 415 matching lines @@
 using WTF::partitionAlloc;
 using WTF::partitionFree;
 using WTF::partitionAllocGeneric;
 using WTF::partitionFreeGeneric;
 using WTF::partitionReallocGeneric;
 using WTF::partitionAllocActualSize;
 using WTF::partitionAllocSupportsGetSize;
 using WTF::partitionAllocGetSize;
 
 #endif // WTF_PartitionAlloc_h