SkVarAlloc

src/core/SkVarAlloc.cpp

Index: src/core/SkVarAlloc.cpp
diff --git a/src/core/SkVarAlloc.cpp b/src/core/SkVarAlloc.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..53b5e85ee771b3cc1de3ac0bd00f64fb23331792
--- /dev/null
+++ b/src/core/SkVarAlloc.cpp
@@ -0,0 +1,55 @@
+#include "SkVarAlloc.h"
+
+// We use non-standard malloc diagnostic methods to make sure our allocations are sized well.
+#if defined(SK_BUILD_FOR_MAC)
+    #include <malloc/malloc.h>
+#elif defined(SK_BUILD_FOR_LINUX)
+    #include <malloc.h>
+#endif
+
+struct SkVarAlloc::Block {
+    Block* prev;
+    char* data() { return (char*)(this + 1); }
+
+    static Block* Alloc(Block* prev, size_t size, unsigned flags) {
+        SkASSERT(size >= sizeof(Block));
+        Block* b = (Block*)sk_malloc_flags(size, flags);
+        b->prev = prev;
+        return b;
+    }
+};
+
+SkVarAlloc::SkVarAlloc(size_t smallest, float growth)
+    : fByte(NULL)
+    , fLimit(NULL)
+    , fSmallest(SkToUInt(smallest))
+    , fGrowth(growth)
+    , fBlock(NULL) {}
+
+SkVarAlloc::~SkVarAlloc() {
+    Block* b = fBlock;
+    while (b) {
+        Block* prev = b->prev;
+        sk_free(b);
+        b = prev;
+    }
+}
+
+void SkVarAlloc::makeSpace(size_t bytes, unsigned flags) {
+    SkASSERT(SkIsAlignPtr(bytes));
+
+    size_t alloc = fSmallest;
+    while (alloc < bytes + sizeof(Block)) {
+        alloc *= 2;
+    }
+    fBlock = Block::Alloc(fBlock, alloc, flags);
+    fByte = fBlock->data();
+    fLimit = fByte + alloc - sizeof(Block);
+    fSmallest = SkToUInt(fSmallest * fGrowth);

[reed1, 2014/11/12 22:12:25]

I think you may get warnings about float->int conversion here.
I do like the cast to uint to catch the size_t down cast.

[mtklein, 2014/11/12 22:23:39]

Now explicitly truncating.

+
+#if defined(SK_BUILD_FOR_MAC)
+    SkASSERT(alloc == malloc_good_size(alloc));
+#elif defined(SK_BUILD_FOR_LINUX)
+    SkASSERT(alloc == malloc_usable_size(fByte - sizeof(Block)));
+#endif
+}