command_buffer: Implement IdAllocator by recording ranges in an AVL tree

gpu/command_buffer/common/id_allocator_test.cc

 // Copyright (c) 2011 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.
 
 // This file has the unit tests for the IdAllocator class.
 
 #include "gpu/command_buffer/common/id_allocator.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace gpu {
@@ skipping 147 matching lines @@
   allocator->FreeID(1);
   allocator->FreeID(15);
   allocator->FreeIDRange(2, 107);
   ResourceId id11 = allocator->AllocateIDRange(100);
   EXPECT_EQ(1u, id11);
   allocator->FreeID(kMaxPossibleOffset);
   ResourceId id12 = allocator->AllocateIDRange(100);
   EXPECT_EQ(101u, id12);
 
   ResourceId id13 = allocator->AllocateIDAtOrAbove(kMaxPossibleOffset - 2u);
-  EXPECT_EQ(kMaxPossibleOffset, id13);
+  EXPECT_EQ(kMaxPossibleOffset - 2u, id13);
   ResourceId id14 = allocator->AllocateIDRange(3);
   EXPECT_EQ(201u, id14);
 }
 
-TEST_F(IdAllocatorTest, AllocateIDRangeNoWrapInRange) {
+TEST_F(IdAllocatorTest, AllocateIDRangeEndNoEffect) {
   const ResourceId kMaxPossibleOffset = ~static_cast<ResourceId>(0);
 
   IdAllocator* allocator = id_allocator();
   ResourceId id1 = allocator->AllocateIDAtOrAbove(kMaxPossibleOffset - 2u);
   EXPECT_EQ(kMaxPossibleOffset - 2u, id1);
   ResourceId id3 = allocator->AllocateIDRange(3);
   EXPECT_EQ(1u, id3);
   ResourceId id2 = allocator->AllocateIDRange(2);
-  EXPECT_EQ(kMaxPossibleOffset - 1, id2);
+  EXPECT_EQ(4u, id2);
+}
+
+TEST_F(IdAllocatorTest, AllocateFullIDRange) {
+  const uint32_t kMaxPossibleRange = ~static_cast<uint32_t>(0u);
+  const ResourceId kFreedId = 555u;
+  IdAllocator* allocator = id_allocator();
+
+  ResourceId id1 = allocator->AllocateIDRange(kMaxPossibleRange);
+  EXPECT_EQ(1u, id1);
+  ResourceId id2 = allocator->AllocateID();
+  EXPECT_EQ(0u, id2);
+  allocator->FreeID(kFreedId);
+  ResourceId id3 = allocator->AllocateID();
+  EXPECT_EQ(kFreedId, id3);
+  ResourceId id4 = allocator->AllocateID();
+  EXPECT_EQ(0u, id4);
+  allocator->FreeID(kFreedId + 1u);
+  allocator->FreeID(kFreedId + 3u);
+  allocator->FreeID(kFreedId + 2u);
+  allocator->FreeID(kFreedId + 5u);
+  allocator->FreeID(kFreedId + 4u);
+  ResourceId id5 = allocator->AllocateIDRange(5);
+  EXPECT_EQ(kFreedId + 1u, id5);
+}
+
+TEST_F(IdAllocatorTest, AllocateIDRangeNoWrapInRange) {
+  const uint32_t kMaxPossibleRange = ~static_cast<uint32_t>(0u);
+  const ResourceId kAllocId = 10u;
+  IdAllocator* allocator = id_allocator();
+
+  ResourceId id1 = allocator->AllocateIDAtOrAbove(kAllocId);
+  EXPECT_EQ(kAllocId, id1);
+  ResourceId id2 = allocator->AllocateIDRange(kMaxPossibleRange - 5u);
+  EXPECT_EQ(0u, id2);
+}
+TEST_F(IdAllocatorTest, AllocateIdMax) {
+  IdAllocator* allocator = id_allocator();
+  ResourceId id =
+      allocator->AllocateIDRange(std::numeric_limits<uint32_t>::max());
+  EXPECT_EQ(1u, id);
+  allocator->FreeIDRange(id, std::numeric_limits<uint32_t>::max() - 1u);
+  ResourceId id2 =
+      allocator->AllocateIDRange(std::numeric_limits<uint32_t>::max());
+  EXPECT_EQ(0u, id2);
+  allocator->FreeIDRange(id, std::numeric_limits<uint32_t>::max());
+  ResourceId id3 =
+      allocator->AllocateIDRange(std::numeric_limits<uint32_t>::max());
+  EXPECT_EQ(1u, id3);
 }
 
 }  // namespace gpu