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d5ddd14ee1
Add MapInsertOrReplace<>() to insert a key-value pair into a map if the key is not already present, or replace the existing value for key if the key is present. The original value can optionally be returned to the caller in this case. Map insertions now use either MapInsertOrReplace<>() or std::map<>::insert() directly. Use MapInsertOrReplace<>() when the map should be updated to contain a mapping from a key to a value regardless of whether the key is already present. Use std::map<>::insert() to insert a mapping from a key to a value without replacing any existing mapping from a key, if present. If it is important to know whether an existing mapping from a key was present, use the returned std::pair<>.second. If it is important to know the existing value, use the returned std::pair<>.first->second. This change has a slight positive impact on performance. TEST=crashpad_util_test MapInsert.MapInsertOrReplace and others BUG= R=scottmg@chromium.org Review URL: https://codereview.chromium.org/1044273002
68 lines
2.5 KiB
C++
68 lines
2.5 KiB
C++
// Copyright 2014 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "minidump/minidump_thread_id_map.h"
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#include <limits>
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#include <set>
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#include <utility>
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#include "base/logging.h"
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#include "base/numerics/safe_conversions.h"
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#include "snapshot/thread_snapshot.h"
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namespace crashpad {
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void BuildMinidumpThreadIDMap(
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const std::vector<const ThreadSnapshot*>& thread_snapshots,
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MinidumpThreadIDMap* thread_id_map) {
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DCHECK(thread_id_map->empty());
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// First, try truncating each 64-bit thread ID to 32 bits. If that’s possible
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// for each unique 64-bit thread ID, then this will be used as the mapping.
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// This preserves as much of the original thread ID as possible when feasible.
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bool collision = false;
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std::set<uint32_t> thread_ids_32;
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for (const ThreadSnapshot* thread_snapshot : thread_snapshots) {
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uint64_t thread_id_64 = thread_snapshot->ThreadID();
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if (thread_id_map->find(thread_id_64) == thread_id_map->end()) {
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uint32_t thread_id_32 = static_cast<uint32_t>(thread_id_64);
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if (!thread_ids_32.insert(thread_id_32).second) {
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collision = true;
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break;
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}
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thread_id_map->insert(std::make_pair(thread_id_64, thread_id_32));
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}
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}
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if (collision) {
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// Since there was a collision, go back and assign each unique 64-bit thread
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// ID its own sequential 32-bit equivalent. The 32-bit thread IDs will not
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// bear any resemblance to the original 64-bit thread IDs.
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thread_id_map->clear();
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for (const ThreadSnapshot* thread_snapshot : thread_snapshots) {
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uint64_t thread_id_64 = thread_snapshot->ThreadID();
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if (thread_id_map->find(thread_id_64) == thread_id_map->end()) {
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uint32_t thread_id_32 =
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base::checked_cast<uint32_t>(thread_id_map->size());
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thread_id_map->insert(std::make_pair(thread_id_64, thread_id_32));
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}
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}
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DCHECK_LE(thread_id_map->size(), std::numeric_limits<uint32_t>::max());
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}
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}
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} // namespace crashpad
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