In CompositeHTTPBodyStream, coalesce small GetBytesBuffer()s to better fill the buffer.

R=mark@chromium.org

Review URL: https://codereview.chromium.org/707223002

util/net/http_body.cc

@@ -97,20 +97,25 @@ CompositeHTTPBodyStream::~CompositeHTTPBodyStream() {
 }
 
 ssize_t CompositeHTTPBodyStream::GetBytesBuffer(uint8_t* buffer,
-                                                size_t max_len) {
+                                                size_t buffer_len) {
-  if (current_part_ == parts_.end())
+  ssize_t max_len = std::min(
-    return 0;
+      buffer_len, implicit_cast<size_t>(std::numeric_limits<ssize_t>::max()));
+  ssize_t bytes_copied = 0;
+  while (bytes_copied < max_len && current_part_ != parts_.end()) {
+    ssize_t this_read = (*current_part_)->GetBytesBuffer(
+        buffer + bytes_copied, max_len - bytes_copied);
 
-  ssize_t rv = (*current_part_)->GetBytesBuffer(buffer, max_len);
+    if (this_read == 0) {
-
-  if (rv == 0) {
       // If the current part has returned 0 indicating EOF, advance the current
-    // part and call recursively to try again.
+      // part and try again.
       ++current_part_;
-    return GetBytesBuffer(buffer, max_len);
+    } else if (this_read < 0) {
+      return this_read;
+    }
+    bytes_copied += this_read;
   }
 
-  return rv;
+  return bytes_copied;
 }
 
 }  // namespace crashpad

util/net/http_body_test.cc

@@ -214,7 +214,7 @@ TEST_P(CompositeHTTPBodyStreamBufferSize, StringsAndFile) {
 
 INSTANTIATE_TEST_CASE_P(VariableBufferSize,
                         CompositeHTTPBodyStreamBufferSize,
-                        testing::Values(1, 2, 9, 16, 31, 128));
+                        testing::Values(1, 2, 9, 16, 31, 128, 1024));
 
 }  // namespace
 }  // namespace test