Initial version of Blimp BlobCache.

blimp/common/compositor/webp_decoder.cc

Index: blimp/common/compositor/webp_decoder.cc
diff --git a/blimp/common/compositor/webp_decoder.cc b/blimp/common/compositor/webp_decoder.cc
index 7f4d3637d618eaed36ec202bc78e0aa0a6d9db8a..e98b0c19d3219c2d5878c6acfa802fd28d8eea49 100644
--- a/blimp/common/compositor/webp_decoder.cc
+++ b/blimp/common/compositor/webp_decoder.cc
@@ -4,12 +4,28 @@
 
 #include "blimp/common/compositor/webp_decoder.h"
 
+#include "base/lazy_instance.h"
 #include "base/logging.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/sha1.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "blimp/common/blob_cache/blob_cache.h"
+#include "blimp/common/blob_cache/in_memory_blob_cache.h"
+#include "blimp/common/blob_cache/sha1_util.h"
+#include "blimp/common/proto/blob_cache.pb.h"
 #include "third_party/libwebp/webp/decode.h"
 #include "third_party/libwebp/webp/demux.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
 namespace blimp {
+namespace {
+
+// TODO(nyquist): Make this not be infinite size.
+static base::LazyInstance<InMemoryBlobCache> g_blob_cache =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
 
 bool WebPDecoder(const void* input, size_t input_size, SkBitmap* bitmap) {
   DCHECK(bitmap);
@@ -21,13 +37,53 @@ bool WebPDecoder(const void* input, size_t input_size, SkBitmap* bitmap) {
     return false;
   }
 
-  // Treat the input as uint8_t.
-  WebPData data = {reinterpret_cast<const uint8_t*>(input), input_size};
+  BlobCacheImageMetadata deserialized;
+  int signed_size = base::checked_cast<int>(input_size);
+  if (!deserialized.ParseFromArray(input, signed_size)) {
+    LOG(WARNING) << "Failed to parse BlobCacheImageMetadata";
+    return false;
+  }
+
+  // The cache uses the SHA1 hex string of the ID.
+  if (deserialized.id().length() != base::kSHA1Length) {
+    LOG(WARNING) << "Length of ID is not base::kSHA1Length, but "

[vmpstr, 2016/04/18 19:38:11]

Log base::kSHA1Length as well for posterity?

[nyquist, 2016/04/18 20:12:02]

Done.

+                 << deserialized.id().length();
+    return false;
+  }
+  std::string hex_id = FormatBlobId(deserialized.id());
+
+  // Declared here to still be in scope while decoding WebP data.
+  BlobData cached;
+
+  // Set to true if the client already has the data in its cache. If it does not
+  // keeping |found_in_cache| as false will trigger caching the input in the
+  // end of this function.
+  bool found_in_cache = false;
+
+  // Used later to decode the image and is initialized either based on a cached
+  // item or from the |payload| of the proto.
+  WebPData webp_data;
+
+  if (g_blob_cache.Get().Contains(deserialized.id())) {
+    // The image was found in the cache, so decode using cached data.
+    cached = g_blob_cache.Get().Get(deserialized.id());

[vmpstr, 2016/04/18 19:38:11]

Honestly, I'm not sure how I feel about BlobData being a scoped_refptr. This
looks like it's doing some sort of a deep copy, so one would be tempted to
rewrite this to bind it to a const ref or something. However, it's cheap because
it's a pointer... A little non obvious, that's all.

This is just a comment, not a suggestion for a fix or anything :P

[nyquist, 2016/04/18 20:12:02]

Okay. I'll keep that in mind. If we realize going forward that it's easy to make
such mistakes, we should definitely look into changing it.

+    webp_data.bytes = reinterpret_cast<const uint8_t*>(cached->data.data());
+    webp_data.size = cached->data.size();
+    DVLOG(2) << "Found SHA1 " << hex_id << " with size = " << webp_data.size;
+    found_in_cache = true;
+  } else {
+    // The image was not found in the cache, so decode using the payload.
+    DCHECK(deserialized.has_payload());
+    webp_data.bytes =
+        reinterpret_cast<const uint8_t*>(deserialized.payload().c_str());
+    webp_data.size = deserialized.payload().size();
+  }
 
   // Read WebP feature information into |config.input|, which is a
   // WebPBitstreamFeatures. It contains information such as width, height and
   // whether the WebP image has an alpha channel or not.
-  if (WebPGetFeatures(data.bytes, data.size, &config.input) != VP8_STATUS_OK) {
+  if (WebPGetFeatures(webp_data.bytes, webp_data.size, &config.input) !=
+      VP8_STATUS_OK) {
     LOG(WARNING) << "Failed to get WebP features.";
     return false;
   }
@@ -59,7 +115,8 @@ bool WebPDecoder(const void* input, size_t input_size, SkBitmap* bitmap) {
   config.output = decoderBuffer;
 
   // Decode the input data into the bitmap buffer.
-  bool success = WebPDecode(data.bytes, data.size, &config) == VP8_STATUS_OK;
+  bool success =
+      WebPDecode(webp_data.bytes, webp_data.size, &config) == VP8_STATUS_OK;
 
   // Now free the buffer. It is safe to call this even when the buffer is
   // external and not allocated by WebPDecode.
@@ -69,6 +126,15 @@ bool WebPDecoder(const void* input, size_t input_size, SkBitmap* bitmap) {
     LOG(WARNING) << "Failed to decode WebP data.";
     return false;
   }
+
+  if (!found_in_cache) {
+    DVLOG(2) << "Inserting image to cache with SHA1: " << hex_id
+             << " size: " << webp_data.size;
+    BlobData to_cache(new base::RefCountedData<const std::string>(std::string(
+        reinterpret_cast<const char*>(webp_data.bytes), webp_data.size)));
+    g_blob_cache.Get().Put(deserialized.id(), std::move(to_cache));
+  }
+
   return true;
 }