Change Pickle to double its capacity by default, rather than increasing

incrementally, when it needs to expand on writing data.

BUG=8760
Review URL: http://codereview.chromium.org/46056

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@11769 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 6 insertions, 4 deletions

diff --git a/base/pickle.cc b/base/pickle.cc
index d525e3f..1aeb1f4 100644
--- a/base/pickle.cc
+++ b/base/pickle.cc
@@ -263,7 +263,8 @@ char* Pickle::BeginWrite(size_t length) {
   size_t offset = AlignInt(header_->payload_size, sizeof(uint32));
 
   size_t new_size = offset + length;
-  if (header_size_ + new_size > capacity_ && !Resize(header_size_ + new_size))
+  size_t needed_size = header_size_ + new_size;
+  if (needed_size > capacity_ && !Resize(std::max(capacity_ * 2, needed_size)))
     return NULL;
 
 #ifdef ARCH_CPU_64_BITS
diff --git a/base/pickle_unittest.cc b/base/pickle_unittest.cc
index a3fa1eb..48ab1cd 100644
--- a/base/pickle_unittest.cc
+++ b/base/pickle_unittest.cc
@@ -167,7 +167,8 @@ TEST(PickleTest, Resize) {
       static_cast<int>(payload_size_after_header - sizeof(uint32)));
   size_t cur_payload = payload_size_after_header;
 
-  EXPECT_EQ(pickle.capacity(), unit);
+  // note: we assume 'unit' is a power of 2
+  EXPECT_EQ(unit, pickle.capacity());
   EXPECT_EQ(pickle.payload_size(), payload_size_after_header);
 
   // fill out a full page (noting data header)
@@ -176,10 +177,10 @@ TEST(PickleTest, Resize) {
   EXPECT_EQ(unit * 2, pickle.capacity());
   EXPECT_EQ(cur_payload, pickle.payload_size());
 
-  // one more byte should expand the capacity by one unit
+  // one more byte should double the capacity
   pickle.WriteData(data_ptr, 1);
   cur_payload += 5;
-  EXPECT_EQ(unit * 3, pickle.capacity());
+  EXPECT_EQ(unit * 4, pickle.capacity());
   EXPECT_EQ(cur_payload, pickle.payload_size());
 }