Initial version of Blimp BlobCache.

blimp/engine/renderer/engine_image_serialization_processor.cc

Index: blimp/engine/renderer/engine_image_serialization_processor.cc
diff --git a/blimp/engine/renderer/engine_image_serialization_processor.cc b/blimp/engine/renderer/engine_image_serialization_processor.cc
index ffecf3576df9c7f9e89fe49a67294ffaee7a530f..56d1fd7eb3e31c88e849d9734fb7370a08b55fa4 100644
--- a/blimp/engine/renderer/engine_image_serialization_processor.cc
+++ b/blimp/engine/renderer/engine_image_serialization_processor.cc
@@ -5,10 +5,16 @@
 #include "blimp/engine/renderer/engine_image_serialization_processor.h"
 
 #include <stddef.h>
+#include <set>
+#include <string>
 #include <vector>
 
 #include "base/logging.h"
+#include "base/sha1.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
 #include "blimp/common/compositor/webp_decoder.h"
+#include "blimp/common/proto/blob_cache.pb.h"
 #include "content/public/renderer/render_frame.h"
 #include "third_party/libwebp/webp/encode.h"
 #include "third_party/skia/include/core/SkData.h"
@@ -17,6 +23,17 @@
 #include "third_party/skia/include/core/SkUnPreMultiply.h"
 
 namespace {
+
+std::string ToSHA1HexString(const void* data, size_t data_size) {

[Kevin M, 2016/04/13 23:29:53]

Break this out into a library for sharing with client/

[nyquist, 2016/04/14 19:33:23]

Done.

+  unsigned char sha1_hash[base::kSHA1Length];
+  base::SHA1HashBytes(static_cast<const unsigned char*>(data), data_size,
+                      sha1_hash);
+  return base::ToLowerASCII(base::HexEncode(sha1_hash, base::kSHA1Length));
+}
+
+// TODO(nyquist): Add support for changing this from the client.
+std::set<std::string> g_client_cache_contents;

[Kevin M, 2016/04/13 23:29:53]

Use LazyInstance

[nyquist, 2016/04/14 19:33:23]

Done.

+
 // TODO(nyquist): Make sure encoder does not serialize images more than once.
 // See crbug.com/548434.
 class WebPImageEncoder : public SkPixelSerializer {
@@ -25,10 +42,8 @@ class WebPImageEncoder : public SkPixelSerializer {
   ~WebPImageEncoder() override{};
 
   bool onUseEncodedData(const void* data, size_t len) override {
-    const unsigned char* cast_data = static_cast<const unsigned char*>(data);
-    if (len < 14)
-      return false;
-    return !memcmp(cast_data, "RIFF", 4) && !memcmp(cast_data + 8, "WEBPVP", 6);
+    // Always encode even WebP data, to enable caching.
+    return false;
   }
 
   SkData* onEncode(const SkPixmap& pixmap) override {
@@ -83,9 +98,27 @@ class WebPImageEncoder : public SkPixelSerializer {
     if (!success)
       return nullptr;
 
-    // Copy WebP data into SkData. |data| is allocated only on the stack, so
-    // it is automatically deleted after this.
-    return SkData::NewWithCopy(&data.front(), data.size());
+    std::string sha1 = ToSHA1HexString(&data.front(), data.size());
+    if (g_client_cache_contents.find(sha1) == g_client_cache_contents.end()) {
+      g_client_cache_contents.insert(sha1);
+      // Copy WebP data into SkData. |data| is allocated only on the stack, so

[Kevin M, 2016/04/13 23:29:53]

Move comment to top of block or add newline before comment.

Note that this branch indicates cache miss.

[nyquist, 2016/04/14 19:33:23]

Done.

+      // it is automatically deleted after this.
+      VLOG(2) << "Sending image: " << sha1 << " size = " << data.size();
+      return SkData::NewWithCopy(&data.front(), data.size());
+    } else {

[Kevin M, 2016/04/13 23:29:53]

Add comment about cache hit

[nyquist, 2016/04/14 19:33:23]

Done.

+      std::unique_ptr<blimp::BlobCacheImageIdentifier> proto(
+          new blimp::BlobCacheImageIdentifier);
+      proto->set_id(sha1);
+      proto->set_width(picture.width);
+      proto->set_height(picture.height);
+      int signed_size = proto->ByteSize();
+      size_t unsigned_size = base::checked_cast<size_t>(signed_size);
+      std::vector<uint8_t> serialized(unsigned_size);
+      proto->SerializeToArray(serialized.data(), signed_size);
+      // Copy cache identifier proto into SkData.

[Kevin M, 2016/04/13 23:29:53]

Newline before comment.

[nyquist, 2016/04/14 19:33:23]

Done.

+      VLOG(2) << "Sending cached: " << sha1 << " size = " << serialized.size();
+      return SkData::NewWithCopy(serialized.data(), serialized.size());
+    }
   }
 
  private: