Use CompoundBuffer in MessageDecoder.

TEST=Unittests
BUG=None

Review URL: http://codereview.chromium.org/5067001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@66574 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 84 insertions, 0 deletions

diff --git a/remoting/base/compound_buffer.cc b/remoting/base/compound_buffer.cc
index 9e8b8c3..2808f6d 100644
--- a/remoting/base/compound_buffer.cc
+++ b/remoting/base/compound_buffer.cc
@@ -88,6 +88,49 @@ void CompoundBuffer::PrependCopyOf(const char* data, int size) {
   Prepend(buffer, size);
 }
 
+void CompoundBuffer::CropFront(int bytes) {
+  CHECK(!locked_);
+
+  if (total_bytes_ <= bytes) {
+    Clear();
+    return;
+  }
+
+  total_bytes_ -= bytes;
+  while (chunks_.size() > 0 && chunks_.front().size <= bytes) {
+    bytes -= chunks_.front().size;
+    chunks_.pop_front();
+  }
+  if (chunks_.size() > 0 && bytes > 0) {
+    chunks_.front().start += bytes;
+    chunks_.front().size -= bytes;
+    DCHECK_GT(chunks_.front().size, 0);
+    bytes = 0;
+  }
+  DCHECK_EQ(bytes, 0);
+}
+
+void CompoundBuffer::CropBack(int bytes) {
+  CHECK(!locked_);
+
+  if (total_bytes_ <= bytes) {
+    Clear();
+    return;
+  }
+
+  total_bytes_ -= bytes;
+  while (chunks_.size() > 0 && chunks_.back().size <= bytes) {
+    bytes -= chunks_.back().size;
+    chunks_.pop_back();
+  }
+  if (chunks_.size() > 0 && bytes > 0) {
+    chunks_.back().size -= bytes;
+    DCHECK_GT(chunks_.back().size, 0);
+    bytes = 0;
+  }
+  DCHECK_EQ(bytes, 0);
+}
+
 void CompoundBuffer::Lock() {
   locked_ = true;
 }
diff --git a/remoting/base/compound_buffer.h b/remoting/base/compound_buffer.h
index 050182a..1b0a546 100644
--- a/remoting/base/compound_buffer.h
+++ b/remoting/base/compound_buffer.h
@@ -52,6 +52,10 @@ class CompoundBuffer {
   void AppendCopyOf(const char* data, int data_size);
   void PrependCopyOf(const char* data, int data_size);
 
+  // Drop |bytes| bytes from the beginning or the end of the buffer.
+  void CropFront(int bytes);
+  void CropBack(int bytes);
+
   // Current size of the buffer.
   int total_bytes() const { return total_bytes_; }
 
diff --git a/remoting/base/compound_buffer_unittest.cc b/remoting/base/compound_buffer_unittest.cc
index 63ede5a..2b90bfe 100644
--- a/remoting/base/compound_buffer_unittest.cc
+++ b/remoting/base/compound_buffer_unittest.cc
@@ -24,6 +24,9 @@ const int kChunkSizes1[] = {1, 10, 20, -1};
 // Chunk sizes used to test CopyFrom().
 const int kCopySizes0[] = {10, 3, -1};
 const int kCopySizes1[] = {20, -1};
+
+const int kCropSizes[] = {1, -1};
+
 }  // namespace
 
 class CompoundBufferTest : public testing::Test {
@@ -52,6 +55,22 @@ class CompoundBufferTest : public testing::Test {
     EXPECT_TRUE(CompareData(copy, data_->data() + pos, size));
   }
 
+  void TestCropFront(int pos, int size) {
+    CompoundBuffer cropped;
+    cropped.CopyFrom(target_, 0, target_.total_bytes());
+    cropped.CropFront(pos);
+    EXPECT_TRUE(CompareData(cropped, data_->data() + pos,
+                            target_.total_bytes() - pos));
+  }
+
+  void TestCropBack(int pos, int size) {
+    CompoundBuffer cropped;
+    cropped.CopyFrom(target_, 0, target_.total_bytes());
+    cropped.CropBack(pos);
+    EXPECT_TRUE(CompareData(cropped, data_->data(),
+                            target_.total_bytes() - pos));
+  }
+
  protected:
   virtual void SetUp() {
     data_ = new IOBuffer(kDataSize);
@@ -210,6 +229,24 @@ TEST_F(CompoundBufferTest, PrependCopyOf) {
   EXPECT_TRUE(CompareData(target_, data_->data(), kDataSize));
 }
 
+TEST_F(CompoundBufferTest, CropFront) {
+  target_.Clear();
+  IterateOverPieces(kChunkSizes1, NewCallback(
+      static_cast<CompoundBufferTest*>(this), &CompoundBufferTest::Append));
+  IterateOverPieces(kCropSizes, NewCallback(
+        static_cast<CompoundBufferTest*>(this),
+      &CompoundBufferTest::TestCropFront));
+}
+
+TEST_F(CompoundBufferTest, CropBack) {
+  target_.Clear();
+  IterateOverPieces(kChunkSizes1, NewCallback(
+      static_cast<CompoundBufferTest*>(this), &CompoundBufferTest::Append));
+  IterateOverPieces(kCropSizes, NewCallback(
+      static_cast<CompoundBufferTest*>(this),
+      &CompoundBufferTest::TestCropBack));
+}
+
 TEST_F(CompoundBufferTest, CopyFrom) {
   target_.Clear();
   IterateOverPieces(kChunkSizes1, NewCallback(