Initial Commit

absl/base/internal/low_level_alloc_test.cc

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+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/base/internal/low_level_alloc.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <thread>  // NOLINT(build/c++11)
+#include <unordered_map>
+
+#include "absl/base/internal/malloc_hook.h"
+
+namespace absl {
+namespace base_internal {
+namespace {
+
+// This test doesn't use gtest since it needs to test that everything
+// works before main().
+#define TEST_ASSERT(x)                                           \
+  if (!(x)) {                                                    \
+    printf("TEST_ASSERT(%s) FAILED ON LINE %d\n", #x, __LINE__); \
+    abort();                                                     \
+  }
+
+// a block of memory obtained from the allocator
+struct BlockDesc {
+  char *ptr;      // pointer to memory
+  int len;        // number of bytes
+  int fill;       // filled with data starting with this
+};
+
+// Check that the pattern placed in the block d
+// by RandomizeBlockDesc is still there.
+static void CheckBlockDesc(const BlockDesc &d) {
+  for (int i = 0; i != d.len; i++) {
+    TEST_ASSERT((d.ptr[i] & 0xff) == ((d.fill + i) & 0xff));
+  }
+}
+
+// Fill the block "*d" with a pattern
+// starting with a random byte.
+static void RandomizeBlockDesc(BlockDesc *d) {
+  d->fill = rand() & 0xff;
+  for (int i = 0; i != d->len; i++) {
+    d->ptr[i] = (d->fill + i) & 0xff;
+  }
+}
+
+// Use to indicate to the malloc hooks that
+// this calls is from LowLevelAlloc.
+static bool using_low_level_alloc = false;
+
+// n times, toss a coin, and based on the outcome
+// either allocate a new block or deallocate an old block.
+// New blocks are placed in a std::unordered_map with a random key
+// and initialized with RandomizeBlockDesc().
+// If keys conflict, the older block is freed.
+// Old blocks are always checked with CheckBlockDesc()
+// before being freed.  At the end of the run,
+// all remaining allocated blocks are freed.
+// If use_new_arena is true, use a fresh arena, and then delete it.
+// If call_malloc_hook is true and user_arena is true,
+// allocations and deallocations are reported via the MallocHook
+// interface.
+static void Test(bool use_new_arena, bool call_malloc_hook, int n) {
+  typedef std::unordered_map<int, BlockDesc> AllocMap;
+  AllocMap allocated;
+  AllocMap::iterator it;
+  BlockDesc block_desc;
+  int rnd;
+  LowLevelAlloc::Arena *arena = 0;
+  if (use_new_arena) {
+    int32_t flags = call_malloc_hook ? LowLevelAlloc::kCallMallocHook : 0;
+    arena = LowLevelAlloc::NewArena(flags, LowLevelAlloc::DefaultArena());
+  }
+  for (int i = 0; i != n; i++) {
+    if (i != 0 && i % 10000 == 0) {
+      printf(".");
+      fflush(stdout);
+    }
+
+    switch (rand() & 1) {      // toss a coin
+    case 0:     // coin came up heads: add a block
+      using_low_level_alloc = true;
+      block_desc.len = rand() & 0x3fff;
+      block_desc.ptr =
+        reinterpret_cast<char *>(
+                        arena == 0
+                        ? LowLevelAlloc::Alloc(block_desc.len)
+                        : LowLevelAlloc::AllocWithArena(block_desc.len, arena));
+      using_low_level_alloc = false;
+      RandomizeBlockDesc(&block_desc);
+      rnd = rand();
+      it = allocated.find(rnd);
+      if (it != allocated.end()) {
+        CheckBlockDesc(it->second);
+        using_low_level_alloc = true;
+        LowLevelAlloc::Free(it->second.ptr);
+        using_low_level_alloc = false;
+        it->second = block_desc;
+      } else {
+        allocated[rnd] = block_desc;
+      }
+      break;
+    case 1:     // coin came up tails: remove a block
+      it = allocated.begin();
+      if (it != allocated.end()) {
+        CheckBlockDesc(it->second);
+        using_low_level_alloc = true;
+        LowLevelAlloc::Free(it->second.ptr);
+        using_low_level_alloc = false;
+        allocated.erase(it);
+      }
+      break;
+    }
+  }
+  // remove all remaining blocks
+  while ((it = allocated.begin()) != allocated.end()) {
+    CheckBlockDesc(it->second);
+    using_low_level_alloc = true;
+    LowLevelAlloc::Free(it->second.ptr);
+    using_low_level_alloc = false;
+    allocated.erase(it);
+  }
+  if (use_new_arena) {
+    TEST_ASSERT(LowLevelAlloc::DeleteArena(arena));
+  }
+}
+
+// used for counting allocates and frees
+static int32_t allocates;
+static int32_t frees;
+
+// ignore uses of the allocator not triggered by our test
+static std::thread::id* test_tid;
+
+// called on each alloc if kCallMallocHook specified
+static void AllocHook(const void *p, size_t size) {
+  if (using_low_level_alloc) {
+    if (*test_tid == std::this_thread::get_id()) {
+      allocates++;
+    }
+  }
+}
+
+// called on each free if kCallMallocHook specified
+static void FreeHook(const void *p) {
+  if (using_low_level_alloc) {
+    if (*test_tid == std::this_thread::get_id()) {
+      frees++;
+    }
+  }
+}
+
+// LowLevelAlloc is designed to be safe to call before main().
+static struct BeforeMain {
+  BeforeMain() {
+    test_tid = new std::thread::id(std::this_thread::get_id());
+    TEST_ASSERT(MallocHook::AddNewHook(&AllocHook));
+    TEST_ASSERT(MallocHook::AddDeleteHook(&FreeHook));
+    TEST_ASSERT(allocates == 0);
+    TEST_ASSERT(frees == 0);
+    Test(false, false, 50000);
+    TEST_ASSERT(allocates != 0);  // default arena calls hooks
+    TEST_ASSERT(frees != 0);
+    for (int i = 0; i != 16; i++) {
+      bool call_hooks = ((i & 1) == 1);
+      allocates = 0;
+      frees = 0;
+      Test(true, call_hooks, 15000);
+      if (call_hooks) {
+        TEST_ASSERT(allocates > 5000);  // arena calls hooks
+        TEST_ASSERT(frees > 5000);
+      } else {
+        TEST_ASSERT(allocates == 0);  // arena doesn't call hooks
+        TEST_ASSERT(frees == 0);
+      }
+    }
+    TEST_ASSERT(MallocHook::RemoveNewHook(&AllocHook));
+    TEST_ASSERT(MallocHook::RemoveDeleteHook(&FreeHook));
+  }
+} before_main;
+
+}  // namespace
+}  // namespace base_internal
+}  // namespace absl
+
+int main(int argc, char *argv[]) {
+  // The actual test runs in the global constructor of `before_main`.
+  printf("PASS\n");
+  return 0;
+}