[ON HOLD] Implement pull-based design for content decoding

net/filter/brotli_filter.cc

Index: net/filter/brotli_filter.cc
diff --git a/net/filter/brotli_filter.cc b/net/filter/brotli_filter.cc
deleted file mode 100644
index 41f507c6d45fcf8073398d02dfef017673ede078..0000000000000000000000000000000000000000
--- a/net/filter/brotli_filter.cc
+++ /dev/null
@@ -1,218 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "net/filter/brotli_filter.h"
-
-#include "base/bit_cast.h"
-#include "base/macros.h"
-#include "base/metrics/histogram_macros.h"
-#include "base/numerics/safe_conversions.h"
-#include "base/numerics/safe_math.h"
-#include "third_party/brotli/dec/decode.h"
-
-namespace net {
-
-namespace {
-const uint8_t kGzipHeader[] = {0x1f, 0x8b, 0x08};
-}
-
-// BrotliFilter applies Brotli content decoding to a data stream.
-// Brotli format specification: http://www.ietf.org/id/draft-alakuijala-brotli
-//
-// BrotliFilter is a subclass of Filter. See the latter's header file filter.h
-// for sample usage.
-class BrotliFilter : public Filter {
- public:
-  BrotliFilter(FilterType type)
-      : Filter(type),
-        decoding_status_(DecodingStatus::DECODING_IN_PROGRESS),
-        used_memory_(0),
-        used_memory_maximum_(0),
-        consumed_bytes_(0),
-        produced_bytes_(0),
-        gzip_header_detected_(true) {
-    brotli_state_ = BrotliCreateState(BrotliFilter::AllocateMemory,
-                                      BrotliFilter::FreeMemory, this);
-    CHECK(brotli_state_);
-  }
-
-  ~BrotliFilter() override {
-    BrotliErrorCode error_code = BrotliGetErrorCode(brotli_state_);
-    BrotliDestroyState(brotli_state_);
-    brotli_state_ = nullptr;
-    DCHECK(used_memory_ == 0);
-
-    // Don't report that gzip header was detected in case of lack of input.
-    gzip_header_detected_ &= (consumed_bytes_ >= sizeof(kGzipHeader));
-
-    UMA_HISTOGRAM_ENUMERATION(
-        "BrotliFilter.Status", static_cast<int>(decoding_status_),
-        static_cast<int>(DecodingStatus::DECODING_STATUS_COUNT));
-    UMA_HISTOGRAM_BOOLEAN("BrotliFilter.GzipHeaderDetected",
-                          gzip_header_detected_);
-    if (decoding_status_ == DecodingStatus::DECODING_DONE) {
-      // CompressionPercent is undefined when there is no output produced.
-      if (produced_bytes_ != 0) {
-        UMA_HISTOGRAM_PERCENTAGE(
-            "BrotliFilter.CompressionPercent",
-            static_cast<int>((consumed_bytes_ * 100) / produced_bytes_));
-      }
-    }
-    if (error_code < 0) {
-      UMA_HISTOGRAM_ENUMERATION("BrotliFilter.ErrorCode",
-                                -static_cast<int>(error_code),
-                                1 - BROTLI_LAST_ERROR_CODE);
-    }
-
-    // All code here is for gathering stats, and can be removed when
-    // BrotliFilter is considered stable.
-    static const int kBuckets = 48;
-    static const int64_t kMaxKb = 1 << (kBuckets / 3);  // 64MiB in KiB
-    UMA_HISTOGRAM_CUSTOM_COUNTS("BrotliFilter.UsedMemoryKB",
-                                used_memory_maximum_ / 1024, 1, kMaxKb,
-                                kBuckets);
-  }
-
-  // Decodes the pre-filter data and writes the output into the |dest_buffer|
-  // passed in.
-  // The function returns FilterStatus. See filter.h for its description.
-  //
-  // Upon entry, |*dest_len| is the total size (in number of chars) of the
-  // destination buffer. Upon exit, |*dest_len| is the actual number of chars
-  // written into the destination buffer.
-  //
-  // This function will fail if there is no pre-filter data in the
-  // |stream_buffer_|. On the other hand, |*dest_len| can be 0 upon successful
-  // return. For example, decompressor may process some pre-filter data
-  // but not produce output yet.
-  FilterStatus ReadFilteredData(char* dest_buffer, int* dest_len) override {
-    if (!dest_buffer || !dest_len)
-      return Filter::FILTER_ERROR;
-
-    if (decoding_status_ == DecodingStatus::DECODING_DONE) {
-      *dest_len = 0;
-      return Filter::FILTER_DONE;
-    }
-
-    if (decoding_status_ != DecodingStatus::DECODING_IN_PROGRESS)
-      return Filter::FILTER_ERROR;
-
-    size_t output_buffer_size = base::checked_cast<size_t>(*dest_len);
-    size_t input_buffer_size = base::checked_cast<size_t>(stream_data_len_);
-
-    size_t available_in = input_buffer_size;
-    const uint8_t* next_in = bit_cast<uint8_t*>(next_stream_data_);
-    size_t available_out = output_buffer_size;
-    uint8_t* next_out = bit_cast<uint8_t*>(dest_buffer);
-    size_t total_out = 0;
-
-    // Check if start of the input stream looks like gzip stream.
-    for (size_t i = consumed_bytes_; i < sizeof(kGzipHeader); ++i) {
-      if (!gzip_header_detected_)
-        break;
-      size_t j = i - consumed_bytes_;
-      if (j < available_in && kGzipHeader[i] != next_in[j])
-        gzip_header_detected_ = false;
-    }
-
-    BrotliResult result =
-        BrotliDecompressStream(&available_in, &next_in, &available_out,
-                               &next_out, &total_out, brotli_state_);
-
-    CHECK(available_in <= input_buffer_size);
-    CHECK(available_out <= output_buffer_size);
-    consumed_bytes_ += input_buffer_size - available_in;
-    produced_bytes_ += output_buffer_size - available_out;
-
-    base::CheckedNumeric<size_t> safe_bytes_written(output_buffer_size);
-    safe_bytes_written -= available_out;
-    int bytes_written =
-        base::checked_cast<int>(safe_bytes_written.ValueOrDie());
-
-    switch (result) {
-      case BROTLI_RESULT_NEEDS_MORE_OUTPUT:
-      // Fall through.
-      case BROTLI_RESULT_SUCCESS:
-        *dest_len = bytes_written;
-        stream_data_len_ = base::checked_cast<int>(available_in);
-        next_stream_data_ = bit_cast<char*>(next_in);
-        if (result == BROTLI_RESULT_SUCCESS) {
-          decoding_status_ = DecodingStatus::DECODING_DONE;
-          return Filter::FILTER_DONE;
-        }
-        return Filter::FILTER_OK;
-
-      case BROTLI_RESULT_NEEDS_MORE_INPUT:
-        *dest_len = bytes_written;
-        stream_data_len_ = 0;
-        next_stream_data_ = nullptr;
-        return Filter::FILTER_NEED_MORE_DATA;
-
-      default:
-        decoding_status_ = DecodingStatus::DECODING_ERROR;
-        return Filter::FILTER_ERROR;
-    }
-  }
-
- private:
-  static void* AllocateMemory(void* opaque, size_t size) {
-    BrotliFilter* filter = reinterpret_cast<BrotliFilter*>(opaque);
-    return filter->AllocateMemoryInternal(size);
-  }
-
-  static void FreeMemory(void* opaque, void* address) {
-    BrotliFilter* filter = reinterpret_cast<BrotliFilter*>(opaque);
-    filter->FreeMemoryInternal(address);
-  }
-
-  void* AllocateMemoryInternal(size_t size) {
-    size_t* array = reinterpret_cast<size_t*>(malloc(size + sizeof(size_t)));
-    if (!array)
-      return nullptr;
-    used_memory_ += size;
-    if (used_memory_maximum_ < used_memory_)
-      used_memory_maximum_ = used_memory_;
-    array[0] = size;
-    return &array[1];
-  }
-
-  void FreeMemoryInternal(void* address) {
-    if (!address)
-      return;
-    size_t* array = reinterpret_cast<size_t*>(address);
-    used_memory_ -= array[-1];
-    free(&array[-1]);
-  }
-
-  // Reported in UMA and must be kept in sync with the histograms.xml file.
-  enum class DecodingStatus : int {
-    DECODING_IN_PROGRESS = 0,
-    DECODING_DONE,
-    DECODING_ERROR,
-
-    DECODING_STATUS_COUNT
-    // DECODING_STATUS_COUNT must always be the last element in this enum.
-  };
-
-  // Tracks the status of decoding.
-  // This variable is updated only by ReadFilteredData.
-  DecodingStatus decoding_status_;
-
-  BrotliState* brotli_state_;
-
-  size_t used_memory_;
-  size_t used_memory_maximum_;
-  size_t consumed_bytes_;
-  size_t produced_bytes_;
-
-  bool gzip_header_detected_;
-
-  DISALLOW_COPY_AND_ASSIGN(BrotliFilter);
-};
-
-Filter* CreateBrotliFilter(Filter::FilterType type_id) {
-  return new BrotliFilter(type_id);
-}
-
-}  // namespace net