Add SimpleStringDictionary and its test.

TEST=client_test SimpleStringDictionary*.*
R=rsesek@chromium.org

Review URL: https://codereview.chromium.org/489993002

client/client.gyp

@@ -26,6 +26,8 @@
       'sources': [
         'capture_context_mac.h',
         'capture_context_mac.S',
+        'simple_string_dictionary.cc',
+        'simple_string_dictionary.h',
       ],
     },
     {
@@ -42,6 +44,7 @@
       ],
       'sources': [
         'capture_context_mac_test.cc',
+        'simple_string_dictionary_test.cc',
       ],
     },
   ],

client/simple_string_dictionary.cc

@@ -0,0 +1,46 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// 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 "client/simple_string_dictionary.h"
+
+#include "base/basictypes.h"
+#include "util/stdlib/cxx.h"
+
+#if CXX_LIBRARY_VERSION >= 2011
+#include <type_traits>
+#endif
+
+namespace crashpad {
+namespace {
+
+typedef TSimpleStringDictionary<1, 1, 1> SimpleStringDictionaryForAssertion;
+
+#if CXX_LIBRARY_VERSION >= 2011
+// In C++11, check that TSimpleStringDictionary has standard layout, which is
+// what is actually important.
+COMPILE_ASSERT(
+    std::is_standard_layout<SimpleStringDictionaryForAssertion>::value,
+    SimpleStringDictionary_must_be_standard_layout);
+#else
+// In C++98 (ISO 14882), section 9.5.1 says that a union cannot have a member
+// with a non-trivial ctor, copy ctor, dtor, or assignment operator. Use this
+// property to ensure that Entry remains POD. This doesn’t work for C++11
+// because the requirements for unions have been relaxed.
+union Compile_Assert {
+  SimpleStringDictionaryForAssertion::Entry Compile_Assert__entry_must_be_pod;
+};
+#endif
+
+}  // namespace
+}  // namespace crashpad

client/simple_string_dictionary.h

@@ -0,0 +1,246 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// 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.
+
+#ifndef CRASHPAD_CLIENT_SIMPLE_STRING_DICTIONARY_H_
+#define CRASHPAD_CLIENT_SIMPLE_STRING_DICTIONARY_H_
+
+#include <string.h>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+namespace crashpad {
+
+// Opaque type for the serialized representation of a TSimpleStringDictionary.
+// One is created in TSimpleStringDictionary::Serialize and can be deserialized
+// using one of the constructors.
+struct SerializedSimpleStringDictionary;
+
+// TSimpleStringDictionary is an implementation of a map/dictionary collection
+// that uses a fixed amount of storage, so that it does not perform any dynamic
+// allocations for its operations.
+//
+// The actual map storage (the Entry) is guaranteed to be POD, so that it can be
+// transmitted over various IPC mechanisms.
+//
+// The template parameters control the amount of storage used for the key,
+// value, and map. The KeySize and ValueSize are measured in bytes, not glyphs,
+// and includes space for a \0 byte. This gives space for KeySize-1 and
+// ValueSize-1 characters in an entry. NumEntries is the total number of entries
+// that will fit in the map.
+template <size_t KeySize = 256, size_t ValueSize = 256, size_t NumEntries = 64>
+class TSimpleStringDictionary {
+ public:
+  // Constant and publicly accessible versions of the template parameters.
+  static const size_t key_size = KeySize;
+  static const size_t value_size = ValueSize;
+  static const size_t num_entries = NumEntries;
+
+  // An Entry object is a single entry in the map. If the key is a 0-length
+  // NUL-terminated string, the entry is empty.
+  struct Entry {
+    char key[KeySize];
+    char value[ValueSize];
+
+    bool is_active() const {
+      return key[0] != '\0';
+      }
+  };
+
+  // An Iterator can be used to iterate over all the active entries in a
+  // TSimpleStringDictionary.
+  class Iterator {
+   public:
+    explicit Iterator(const TSimpleStringDictionary& map)
+        : map_(map),
+          current_(0) {
+    }
+
+    // Returns the next entry in the map, or NULL if at the end of the
+    // collection.
+    const Entry* Next() {
+      while (current_ < map_.num_entries) {
+        const Entry* entry = &map_.entries_[current_++];
+        if (entry->is_active()) {
+          return entry;
+        }
+      }
+      return NULL;
+    }
+
+   private:
+    const TSimpleStringDictionary& map_;
+    size_t current_;
+
+    DISALLOW_COPY_AND_ASSIGN(Iterator);
+  };
+
+  TSimpleStringDictionary()
+      : entries_() {
+  }
+
+  TSimpleStringDictionary(const TSimpleStringDictionary& other) {
+    *this = other;
+  }
+
+  TSimpleStringDictionary& operator=(const TSimpleStringDictionary& other) {
+    memcpy(entries_, other.entries_, sizeof(entries_));
+    return *this;
+  }
+
+  // Constructs a map from its serialized form. |map| should be the out
+  // parameter from Serialize() and |size| should be its return value.
+  TSimpleStringDictionary(
+      const SerializedSimpleStringDictionary* map, size_t size) {
+    DCHECK_EQ(size, sizeof(entries_));
+    if (size == sizeof(entries_)) {
+      memcpy(entries_, map, size);
+    }
+  }
+
+  // Returns the number of active key/value pairs. The upper limit for this is
+  // NumEntries.
+  size_t GetCount() const {
+    size_t count = 0;
+    for (size_t i = 0; i < num_entries; ++i) {
+      if (entries_[i].is_active()) {
+        ++count;
+      }
+    }
+    return count;
+  }
+
+  // Given |key|, returns its corresponding |value|. |key| must not be NULL. If
+  // the key is not found, NULL is returned.
+  const char* GetValueForKey(const char* key) const {
+    DCHECK(key);
+    if (!key) {
+      return NULL;
+    }
+
+    const Entry* entry = GetConstEntryForKey(key);
+    if (!entry) {
+      return NULL;
+    }
+
+    return entry->value;
+  }
+
+  // Stores |value| into |key|, replacing the existing value if |key| is already
+  // present. |key| must not be NULL. If |value| is NULL, the key is removed
+  // from the map. If there is no more space in the map, then the operation
+  // silently fails.
+  void SetKeyValue(const char* key, const char* value) {
+    if (!value) {
+      RemoveKey(key);
+      return;
+    }
+
+    DCHECK(key);
+    if (!key) {
+      return;
+    }
+
+    // Key must not be an empty string.
+    DCHECK_NE(key[0], '\0');
+    if (key[0] == '\0') {
+      return;
+    }
+
+    Entry* entry = GetEntryForKey(key);
+
+    // If it does not yet exist, attempt to insert it.
+    if (!entry) {
+      for (size_t i = 0; i < num_entries; ++i) {
+        if (!entries_[i].is_active()) {
+          entry = &entries_[i];
+
+          strncpy(entry->key, key, key_size);
+          entry->key[key_size - 1] = '\0';
+
+          break;
+        }
+      }
+    }
+
+    // If the map is out of space, entry will be NULL.
+    if (!entry) {
+      return;
+    }
+
+#ifndef NDEBUG
+    // Sanity check that the key only appears once.
+    int count = 0;
+    for (size_t i = 0; i < num_entries; ++i) {
+      if (strncmp(entries_[i].key, key, key_size) == 0) {
+        ++count;
+      }
+    }
+    DCHECK_EQ(count, 1);
+#endif
+
+    strncpy(entry->value, value, value_size);
+    entry->value[value_size - 1] = '\0';
+  }
+
+  // Given |key|, removes any associated value. |key| must not be NULL. If the
+  // key is not found, this is a noop.
+  void RemoveKey(const char* key) {
+    DCHECK(key);
+    if (!key) {
+      return;
+    }
+
+    Entry* entry = GetEntryForKey(key);
+    if (entry) {
+      entry->key[0] = '\0';
+      entry->value[0] = '\0';
+    }
+
+    DCHECK_EQ(GetEntryForKey(key), static_cast<void*>(NULL));
+  }
+
+  // Places a serialized version of the map into |map| and returns the size.
+  // Both of these should be passed to the deserializing constructor. Note that
+  // the serialized |map| is scoped to the lifetime of the non-serialized
+  // instance of this class. The |map| can be copied across IPC boundaries.
+  size_t Serialize(const SerializedSimpleStringDictionary** map) const {
+    *map = reinterpret_cast<const SerializedSimpleStringDictionary*>(entries_);
+    return sizeof(entries_);
+  }
+
+ private:
+  const Entry* GetConstEntryForKey(const char* key) const {
+    for (size_t i = 0; i < num_entries; ++i) {
+      if (strncmp(key, entries_[i].key, key_size) == 0) {
+        return &entries_[i];
+      }
+    }
+    return NULL;
+  }
+
+  Entry* GetEntryForKey(const char* key) {
+    return const_cast<Entry*>(GetConstEntryForKey(key));
+  }
+
+  Entry entries_[NumEntries];
+};
+
+// For historical reasons this specialized version is available with the same
+// size factors as a previous implementation.
+typedef TSimpleStringDictionary<256, 256, 64> SimpleStringDictionary;
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_CLIENT_SIMPLE_STRING_DICTIONARY_H_

client/simple_string_dictionary_test.cc

@@ -0,0 +1,295 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// 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 "client/simple_string_dictionary.h"
+
+#include "base/logging.h"
+#include "gtest/gtest.h"
+
+namespace {
+
+using namespace crashpad;
+
+TEST(SimpleStringDictionary, Entry) {
+  typedef TSimpleStringDictionary<5, 9, 15> TestMap;
+  TestMap map;
+
+  const TestMap::Entry* entry = TestMap::Iterator(map).Next();
+  EXPECT_FALSE(entry);
+
+  // Try setting a key/value and then verify.
+  map.SetKeyValue("key1", "value1");
+  entry = TestMap::Iterator(map).Next();
+  ASSERT_TRUE(entry);
+  EXPECT_STREQ(entry->key, "key1");
+  EXPECT_STREQ(entry->value, "value1");
+
+  // Try setting a new value.
+  map.SetKeyValue("key1", "value3");
+  EXPECT_STREQ(entry->value, "value3");
+
+  // Make sure the key didn't change.
+  EXPECT_STREQ(entry->key, "key1");
+
+  // Clear the entry and verify the key and value are empty strings.
+  map.RemoveKey("key1");
+  EXPECT_FALSE(entry->is_active());
+  EXPECT_EQ(strlen(entry->key), 0u);
+  EXPECT_EQ(strlen(entry->value), 0u);
+}
+
+TEST(SimpleStringDictionary, SimpleStringDictionary) {
+  // Make a new dictionary
+  SimpleStringDictionary dict;
+
+  // Set three distinct values on three keys
+  dict.SetKeyValue("key1", "value1");
+  dict.SetKeyValue("key2", "value2");
+  dict.SetKeyValue("key3", "value3");
+
+  EXPECT_NE(dict.GetValueForKey("key1"), "value1");
+  EXPECT_NE(dict.GetValueForKey("key2"), "value2");
+  EXPECT_NE(dict.GetValueForKey("key3"), "value3");
+  EXPECT_EQ(dict.GetCount(), 3u);
+  // try an unknown key
+  EXPECT_FALSE(dict.GetValueForKey("key4"));
+
+  // Remove a key
+  dict.RemoveKey("key3");
+
+  // Now make sure it's not there anymore
+  EXPECT_FALSE(dict.GetValueForKey("key3"));
+
+  // Remove by setting value to NULL
+  dict.SetKeyValue("key2", NULL);
+
+  // Now make sure it's not there anymore
+  EXPECT_FALSE(dict.GetValueForKey("key2"));
+}
+
+TEST(SimpleStringDictionary, CopyAndAssign) {
+  TSimpleStringDictionary<10, 10, 10> map;
+  map.SetKeyValue("one", "a");
+  map.SetKeyValue("two", "b");
+  map.SetKeyValue("three", "c");
+  map.RemoveKey("two");
+  EXPECT_EQ(2u, map.GetCount());
+
+  // Test copy.
+  TSimpleStringDictionary<10, 10, 10> map_copy(map);
+  EXPECT_EQ(2u, map_copy.GetCount());
+  EXPECT_STREQ("a", map_copy.GetValueForKey("one"));
+  EXPECT_STREQ("c", map_copy.GetValueForKey("three"));
+  map_copy.SetKeyValue("four", "d");
+  EXPECT_STREQ("d", map_copy.GetValueForKey("four"));
+  EXPECT_FALSE(map.GetValueForKey("four"));
+
+  // Test assign.
+  TSimpleStringDictionary<10, 10, 10> map_assign;
+  map_assign = map;
+  EXPECT_EQ(2u, map_assign.GetCount());
+  EXPECT_STREQ("a", map_assign.GetValueForKey("one"));
+  EXPECT_STREQ("c", map_assign.GetValueForKey("three"));
+  map_assign.SetKeyValue("four", "d");
+  EXPECT_STREQ("d", map_assign.GetValueForKey("four"));
+  EXPECT_FALSE(map.GetValueForKey("four"));
+
+  map.RemoveKey("one");
+  EXPECT_FALSE(map.GetValueForKey("one"));
+  EXPECT_STREQ("a", map_copy.GetValueForKey("one"));
+  EXPECT_STREQ("a", map_assign.GetValueForKey("one"));
+}
+
+// Add a bunch of values to the dictionary, remove some entries in the middle,
+// and then add more.
+TEST(SimpleStringDictionary, Iterator) {
+  SimpleStringDictionary* dict = new SimpleStringDictionary;
+  ASSERT_TRUE(dict);
+
+  char key[SimpleStringDictionary::key_size];
+  char value[SimpleStringDictionary::value_size];
+
+  const int kDictionaryCapacity = SimpleStringDictionary::num_entries;
+  const int kPartitionIndex = kDictionaryCapacity - 5;
+
+  // We assume at least this size in the tests below
+  ASSERT_GE(kDictionaryCapacity, 64);
+
+  // We'll keep track of the number of key/value pairs we think should be in the
+  // dictionary
+  int expectedDictionarySize = 0;
+
+  // Set a bunch of key/value pairs like key0/value0, key1/value1, ...
+  for (int i = 0; i < kPartitionIndex; ++i) {
+    sprintf(key, "key%d", i);
+    sprintf(value, "value%d", i);
+    dict->SetKeyValue(key, value);
+  }
+  expectedDictionarySize = kPartitionIndex;
+
+  // set a couple of the keys twice (with the same value) - should be nop
+  dict->SetKeyValue("key2", "value2");
+  dict->SetKeyValue("key4", "value4");
+  dict->SetKeyValue("key15", "value15");
+
+  // Remove some random elements in the middle
+  dict->RemoveKey("key7");
+  dict->RemoveKey("key18");
+  dict->RemoveKey("key23");
+  dict->RemoveKey("key31");
+  expectedDictionarySize -= 4;  // we just removed four key/value pairs
+
+  // Set some more key/value pairs like key59/value59, key60/value60, ...
+  for (int i = kPartitionIndex; i < kDictionaryCapacity; ++i) {
+    sprintf(key, "key%d", i);
+    sprintf(value, "value%d", i);
+    dict->SetKeyValue(key, value);
+  }
+  expectedDictionarySize += kDictionaryCapacity - kPartitionIndex;
+
+  // Now create an iterator on the dictionary
+  SimpleStringDictionary::Iterator iter(*dict);
+
+  // We then verify that it iterates through exactly the number of key/value
+  // pairs we expect, and that they match one-for-one with what we would expect.
+  // The ordering of the iteration does not matter...
+
+  // used to keep track of number of occurrences found for key/value pairs
+  int count[kDictionaryCapacity];
+  memset(count, 0, sizeof(count));
+
+  int totalCount = 0;
+
+  const SimpleStringDictionary::Entry* entry;
+  while ((entry = iter.Next())) {
+    totalCount++;
+
+    // Extract keyNumber from a string of the form key<keyNumber>
+    int keyNumber;
+    sscanf(entry->key, "key%d", &keyNumber);
+
+    // Extract valueNumber from a string of the form value<valueNumber>
+    int valueNumber;
+    sscanf(entry->value, "value%d", &valueNumber);
+
+    // The value number should equal the key number since that's how we set them
+    EXPECT_EQ(keyNumber, valueNumber);
+
+    // Key and value numbers should be in proper range: 0 <= keyNumber <
+    // kDictionaryCapacity
+    bool isKeyInGoodRange = (keyNumber >= 0 && keyNumber < kDictionaryCapacity);
+    bool isValueInGoodRange =
+        (valueNumber >= 0 && valueNumber < kDictionaryCapacity);
+    EXPECT_TRUE(isKeyInGoodRange);
+    EXPECT_TRUE(isValueInGoodRange);
+
+    if (isKeyInGoodRange && isValueInGoodRange) {
+      ++count[keyNumber];
+    }
+  }
+
+  // Make sure each of the key/value pairs showed up exactly one time, except
+  // for the ones which we removed.
+  for (size_t i = 0; i < kDictionaryCapacity; ++i) {
+    // Skip over key7, key18, key23, and key31, since we removed them
+    if (!(i == 7 || i == 18 || i == 23 || i == 31)) {
+      EXPECT_EQ(count[i], 1);
+    }
+  }
+
+  // Make sure the number of iterations matches the expected dictionary size.
+  EXPECT_EQ(totalCount, expectedDictionarySize);
+}
+
+TEST(SimpleStringDictionary, AddRemove) {
+  TSimpleStringDictionary<5, 7, 6> map;
+  map.SetKeyValue("rob", "ert");
+  map.SetKeyValue("mike", "pink");
+  map.SetKeyValue("mark", "allays");
+
+  EXPECT_EQ(3u, map.GetCount());
+  EXPECT_STREQ("ert", map.GetValueForKey("rob"));
+  EXPECT_STREQ("pink", map.GetValueForKey("mike"));
+  EXPECT_STREQ("allays", map.GetValueForKey("mark"));
+
+  map.RemoveKey("mike");
+
+  EXPECT_EQ(2u, map.GetCount());
+  EXPECT_FALSE(map.GetValueForKey("mike"));
+
+  map.SetKeyValue("mark", "mal");
+  EXPECT_EQ(2u, map.GetCount());
+  EXPECT_STREQ("mal", map.GetValueForKey("mark"));
+
+  map.RemoveKey("mark");
+  EXPECT_EQ(1u, map.GetCount());
+  EXPECT_FALSE(map.GetValueForKey("mark"));
+}
+
+TEST(SimpleStringDictionary, Serialize) {
+  typedef TSimpleStringDictionary<4, 5, 7> TestMap;
+  TestMap map;
+  map.SetKeyValue("one", "abc");
+  map.SetKeyValue("two", "def");
+  map.SetKeyValue("tre", "hig");
+
+  EXPECT_STREQ("abc", map.GetValueForKey("one"));
+  EXPECT_STREQ("def", map.GetValueForKey("two"));
+  EXPECT_STREQ("hig", map.GetValueForKey("tre"));
+
+  const SerializedSimpleStringDictionary* serialized;
+  size_t size = map.Serialize(&serialized);
+
+  SerializedSimpleStringDictionary* serialized_copy =
+      reinterpret_cast<SerializedSimpleStringDictionary*>(malloc(size));
+  ASSERT_TRUE(serialized_copy);
+  memcpy(serialized_copy, serialized, size);
+
+  TestMap deserialized(serialized_copy, size);
+  free(serialized_copy);
+
+  EXPECT_EQ(3u, deserialized.GetCount());
+  EXPECT_STREQ("abc", deserialized.GetValueForKey("one"));
+  EXPECT_STREQ("def", deserialized.GetValueForKey("two"));
+  EXPECT_STREQ("hig", deserialized.GetValueForKey("tre"));
+}
+
+// Running out of space shouldn't crash.
+TEST(SimpleStringDictionary, OutOfSpace) {
+  TSimpleStringDictionary<3, 2, 2> map;
+  map.SetKeyValue("a", "1");
+  map.SetKeyValue("b", "2");
+  map.SetKeyValue("c", "3");
+  EXPECT_EQ(2u, map.GetCount());
+  EXPECT_FALSE(map.GetValueForKey("c"));
+}
+
+#if DCHECK_IS_ON
+
+TEST(SimpleStringDictionaryDeathTest, NullKey) {
+  TSimpleStringDictionary<4, 6, 6> map;
+  ASSERT_DEATH(map.SetKeyValue(NULL, "hello"), "key");
+
+  map.SetKeyValue("hi", "there");
+  ASSERT_DEATH(map.GetValueForKey(NULL), "key");
+  EXPECT_STREQ("there", map.GetValueForKey("hi"));
+
+  ASSERT_DEATH(map.GetValueForKey(NULL), "key");
+  map.RemoveKey("hi");
+  EXPECT_EQ(0u, map.GetCount());
+}
+
+#endif
+
+}  // namespace