tracing v2: minor refactoring to TraceRingBuffer test helpers

components/tracing/core/trace_ring_buffer_unittest.cc

 // Copyright 2016 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 "components/tracing/core/trace_ring_buffer.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace tracing {
 namespace v2 {
 
 namespace {
 
 const size_t kChunkSize = TraceRingBuffer::Chunk::kSize;
 
-bool overlap(uint8_t* start1, uint8_t* end1, uint8_t* start2, uint8_t* end2) {
-  return start1 < end2 && start2 < end1;
-}
-
 TEST(TraceRingBufferTest, BasicChunkWrapping) {
   const uint32_t kNumChunks = 5;
   const size_t kBufferSize = kChunkSize * kNumChunks;
   std::unique_ptr<uint8_t[]> storage(new uint8_t[kBufferSize]);
   TraceRingBuffer ring_buffer(storage.get(), kBufferSize);
 
+  EXPECT_EQ(0u, ring_buffer.GetNumChunksTaken());
   uint8_t* last_chunk_end = nullptr;
+
   // Fill the buffer twice to test wrapping logic.
   for (uint32_t i = 0; i < kNumChunks * 2; ++i) {
-    TraceRingBuffer::Chunk* chunk = ring_buffer.TakeChunk();
+    TraceRingBuffer::Chunk* chunk = ring_buffer.TakeChunk(42 /* owner */);
     ASSERT_NE(nullptr, chunk);
+    EXPECT_EQ(1u, ring_buffer.GetNumChunksTaken());
+    EXPECT_EQ(42u, chunk->owner());
     const uint32_t chunk_idx = i % kNumChunks;
     EXPECT_EQ(chunk_idx == 0 ? storage.get() : last_chunk_end, chunk->begin());
     const uint32_t kPayloadSize = (chunk_idx + 1) * 8;
     memset(chunk->payload(), static_cast<int>(chunk_idx + 1), kPayloadSize);
     last_chunk_end = chunk->end();
-    ring_buffer.ReturnChunk(chunk, /* used_size = */ kPayloadSize);
+    chunk->set_used_size(kPayloadSize);
+    ring_buffer.ReturnChunk(chunk);
+    EXPECT_EQ(0u, ring_buffer.GetNumChunksTaken());
   }
 
   // Now scrape the |storage| buffer and check its contents.
   for (uint32_t chunk_idx = 0; chunk_idx < kNumChunks; ++chunk_idx) {
     uint8_t* chunk_start = storage.get() + (chunk_idx * kChunkSize);
     const uint32_t kPayloadSize = (chunk_idx + 1) * 8;
     EXPECT_EQ(kPayloadSize, *reinterpret_cast<uint32_t*>(chunk_start));
     for (uint32_t i = 0; i < kPayloadSize; ++i)
       EXPECT_EQ(chunk_idx + 1, *(chunk_start + sizeof(uint32_t) + i));
   }
 }
 
 TEST(TraceRingBufferTest, ChunkBankrupcyDoesNotCrash) {
   const size_t kNumChunks = 2;
   const size_t kBufferSize = TraceRingBuffer::Chunk::kSize * kNumChunks;
   std::unique_ptr<uint8_t[]> storage(new uint8_t[kBufferSize]);
   TraceRingBuffer ring_buffer(storage.get(), kBufferSize);
 
-  TraceRingBuffer::Chunk* chunk1 = ring_buffer.TakeChunk();
+  TraceRingBuffer::Chunk* chunk1 = ring_buffer.TakeChunk(1);
   ASSERT_NE(nullptr, chunk1);
 
-  TraceRingBuffer::Chunk* chunk2 = ring_buffer.TakeChunk();
+  TraceRingBuffer::Chunk* chunk2 = ring_buffer.TakeChunk(1);
   ASSERT_NE(nullptr, chunk2);
 
+  EXPECT_EQ(2u, ring_buffer.GetNumChunksTaken());
+
   for (int i = 0; i < 3; ++i) {
-    TraceRingBuffer::Chunk* bankrupcy_chunk = ring_buffer.TakeChunk();
+    TraceRingBuffer::Chunk* bankrupcy_chunk = ring_buffer.TakeChunk(1);
     ASSERT_NE(nullptr, bankrupcy_chunk);
-    ASSERT_FALSE(overlap(bankrupcy_chunk->begin(), bankrupcy_chunk->end(),
-                         storage.get(), storage.get() + kBufferSize));
+    ASSERT_TRUE(ring_buffer.IsBankrupcyChunkForTesting(bankrupcy_chunk));
 
     // Make sure that the memory of the bankrupty chunk can be dereferenced.
     memset(bankrupcy_chunk->begin(), 0, kChunkSize);
   }
+  EXPECT_EQ(2u, ring_buffer.GetNumChunksTaken());
 
   // Return a chunk and check that the ring buffer is not bankrupt anymore.
-  ring_buffer.ReturnChunk(chunk2, 42);
-  TraceRingBuffer::Chunk* chunk = ring_buffer.TakeChunk();
+  chunk2->set_used_size(42);
+  ring_buffer.ReturnChunk(chunk2);
+  EXPECT_EQ(1u, ring_buffer.GetNumChunksTaken());
+  TraceRingBuffer::Chunk* chunk = ring_buffer.TakeChunk(1);
   ASSERT_NE(nullptr, chunk);
-  ASSERT_TRUE(overlap(chunk->begin(), chunk->end(), storage.get(),
-                      storage.get() + kBufferSize));
+  ASSERT_FALSE(ring_buffer.IsBankrupcyChunkForTesting(chunk));
 }
 
 }  // namespace
 }  // namespace v2
 }  // namespace tracing