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+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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 FRAMEWORK_NATIVE_CMD_DUMPPOOL_H_
+#define FRAMEWORK_NATIVE_CMD_DUMPPOOL_H_
+
+#include <future>
+#include <map>
+#include <queue>
+#include <string>
+
+#include <android-base/file.h>
+#include <android-base/macros.h>
+
+namespace android {
+namespace os {
+namespace dumpstate {
+
+class DumpPoolTest;
+
+/*
+ * A thread pool with the fixed number of threads to execute multiple dump tasks
+ * simultaneously for the dumpstate. The dump task is a callable function. It
+ * could include a file descriptor as a parameter to redirect dump results, if
+ * it needs to output results to the bugreport. This can avoid messing up
+ * bugreport's results when multiple dump tasks are running at the same time.
+ * Takes an example below for the usage of the DumpPool:
+ *
+ * void DumpFoo(int out_fd) {
+ * dprintf(out_fd, "Dump result to out_fd ...");
+ * }
+ * ...
+ * DumpPool pool(tmp_root);
+ * pool.enqueueTaskWithFd("TaskName", &DumpFoo, std::placeholders::_1);
+ * ...
+ * pool.waitForTask("TaskName");
+ *
+ * DumpFoo is a callable function included a out_fd parameter. Using the
+ * enqueueTaskWithFd method in DumpPool to enqueue the task to the pool. The
+ * std::placeholders::_1 is a placeholder for DumpPool to pass a fd argument.
+ */
+class DumpPool {
+ friend class android::os::dumpstate::DumpPoolTest;
+
+ public:
+ /*
+ * Creates a thread pool.
+ *
+ * |tmp_root| A path to a temporary folder for threads to create temporary
+ * files.
+ */
+ explicit DumpPool(const std::string& tmp_root);
+ ~DumpPool();
+
+ /*
+ * Starts the threads in the pool.
+ *
+ * |thread_counts| the number of threads to start.
+ */
+ void start(int thread_counts = MAX_THREAD_COUNT);
+
+ /*
+ * Requests to shutdown the pool and waits until all threads exit the loop.
+ */
+ void shutdown();
+
+ /*
+ * Adds a task into the queue of the thread pool.
+ *
+ * |task_name| The name of the task. It's also the title of the
+ * DurationReporter log.
+ * |f| Callable function to execute the task.
+ * |args| A list of arguments.
+ *
+ * TODO(b/164369078): remove this api to have just one enqueueTask for consistency.
+ */
+ template<class F, class... Args> void enqueueTask(const std::string& task_name, F&& f,
+ Args&&... args) {
+ std::function<void(void)> func = std::bind(std::forward<F>(f),
+ std::forward<Args>(args)...);
+ futures_map_[task_name] = post(task_name, func);
+ if (threads_.empty()) {
+ start();
+ }
+ }
+
+ /*
+ * Adds a task into the queue of the thread pool. The task takes a file
+ * descriptor as a parameter to redirect dump results to a temporary file.
+ *
+ * |task_name| The name of the task. It's also the title of the
+ * DurationReporter log.
+ * |f| Callable function to execute the task.
+ * |args| A list of arguments. A placeholder std::placeholders::_1 as a fd
+ * argument needs to be included here.
+ */
+ template<class F, class... Args> void enqueueTaskWithFd(const std::string& task_name, F&& f,
+ Args&&... args) {
+ std::function<void(int)> func = std::bind(std::forward<F>(f),
+ std::forward<Args>(args)...);
+ futures_map_[task_name] = post(task_name, func);
+ if (threads_.empty()) {
+ start();
+ }
+ }
+
+ /*
+ * Waits until the task is finished. Dumps the task results to the STDOUT_FILENO.
+ */
+ void waitForTask(const std::string& task_name) {
+ waitForTask(task_name, "", STDOUT_FILENO);
+ }
+
+ /*
+ * Waits until the task is finished. Dumps the task results to the specified
+ * out_fd.
+ *
+ * |task_name| The name of the task.
+ * |title| Dump title string to the out_fd, an empty string for nothing.
+ * |out_fd| The target file to dump the result from the task.
+ */
+ void waitForTask(const std::string& task_name, const std::string& title, int out_fd);
+
+ /*
+ * Deletes temporary files created by DumpPool.
+ */
+ void deleteTempFiles();
+
+ static const std::string PREFIX_TMPFILE_NAME;
+
+ private:
+ using Task = std::packaged_task<std::string()>;
+ using Future = std::shared_future<std::string>;
+
+ template<class T> void invokeTask(T dump_func, const std::string& duration_title, int out_fd);
+
+ template<class T> Future post(const std::string& task_name, T dump_func) {
+ Task packaged_task([=]() {
+ std::unique_ptr<TmpFile> tmp_file_ptr = createTempFile();
+ if (!tmp_file_ptr) {
+ return std::string("");
+ }
+ invokeTask(dump_func, task_name, tmp_file_ptr->fd.get());
+ fsync(tmp_file_ptr->fd.get());
+ return std::string(tmp_file_ptr->path);
+ });
+ std::unique_lock lock(lock_);
+ auto future = packaged_task.get_future().share();
+ tasks_.push(std::move(packaged_task));
+ condition_variable_.notify_one();
+ return future;
+ }
+
+ typedef struct {
+ android::base::unique_fd fd;
+ char path[1024];
+ } TmpFile;
+
+ std::unique_ptr<TmpFile> createTempFile();
+ void deleteTempFiles(const std::string& folder);
+ void setThreadName(const pthread_t thread, int id);
+ void loop();
+
+ /*
+ * For test purpose only. Enables or disables logging duration of the task.
+ *
+ * |log_duration| if true, DurationReporter is initiated to log duration of
+ * the task.
+ */
+ void setLogDuration(bool log_duration);
+
+ private:
+ static const int MAX_THREAD_COUNT = 4;
+
+ /* A path to a temporary folder for threads to create temporary files. */
+ std::string tmp_root_;
+ bool shutdown_;
+ bool log_duration_; // For test purpose only, the default value is true.
+ std::mutex lock_; // A lock for the tasks_.
+ std::condition_variable condition_variable_;
+
+ std::vector<std::thread> threads_;
+ std::queue<Task> tasks_;
+ std::map<std::string, Future> futures_map_;
+
+ DISALLOW_COPY_AND_ASSIGN(DumpPool);
+};
+
+} // namespace dumpstate
+} // namespace os
+} // namespace android
+
+#endif //FRAMEWORK_NATIVE_CMD_DUMPPOOL_H_