/*
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* Copyright (C) 2015 The Android Open Source Project
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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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*/
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#ifndef SIMPLE_PERF_EVENT_FD_H_
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#define SIMPLE_PERF_EVENT_FD_H_
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#include <sys/types.h>
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#include <memory>
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#include <string>
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#include <vector>
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#include <android-base/macros.h>
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#include "IOEventLoop.h"
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#include "perf_event.h"
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struct PerfCounter {
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uint64_t value; // The value of the event specified by the perf_event_file.
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uint64_t time_enabled; // The enabled time.
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uint64_t time_running; // The running time.
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uint64_t id; // The id of the perf_event_file.
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};
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// EventFd represents an opened perf_event_file.
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class EventFd {
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public:
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static std::unique_ptr<EventFd> OpenEventFile(const perf_event_attr& attr,
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pid_t tid, int cpu,
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EventFd* group_event_fd,
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bool report_error = true);
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virtual ~EventFd();
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// Give information about this perf_event_file, like (event_name, tid, cpu).
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std::string Name() const;
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uint64_t Id() const;
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pid_t ThreadId() const { return tid_; }
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int Cpu() const { return cpu_; }
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const perf_event_attr& attr() const { return attr_; }
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// It tells the kernel to start counting and recording events specified by
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// this file.
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bool SetEnableEvent(bool enable);
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bool ReadCounter(PerfCounter* counter);
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// Create mapped buffer used to receive records sent by the kernel.
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// mmap_pages should be power of 2.
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virtual bool CreateMappedBuffer(size_t mmap_pages, bool report_error);
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// Share the mapped buffer used by event_fd. The two EventFds should monitor
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// the same event on the same cpu, but have different thread ids.
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bool ShareMappedBuffer(const EventFd& event_fd, bool report_error);
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bool HasMappedBuffer() const { return mmap_data_buffer_size_ != 0; }
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char* GetMappedBuffer(size_t& buffer_size) {
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buffer_size = mmap_data_buffer_size_;
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return mmap_data_buffer_;
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}
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virtual void DestroyMappedBuffer();
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// Return available data in the kernel buffer.
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std::vector<char> GetAvailableMmapData();
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// Return the size of available data in the buffer, and set data_pos to the first available data
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// position in mmap_data_buffer_.
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virtual size_t GetAvailableMmapDataSize(size_t& data_pos);
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// Discard the size of the data we have read, so the kernel can reuse the space for new data.
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virtual void DiscardMmapData(size_t discard_size);
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// [callback] is called when there is data available in the mapped buffer.
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virtual bool StartPolling(IOEventLoop& loop, const std::function<bool()>& callback);
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virtual bool StopPolling();
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protected:
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EventFd(const perf_event_attr& attr, int perf_event_fd,
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const std::string& event_name, pid_t tid, int cpu)
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: attr_(attr),
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perf_event_fd_(perf_event_fd),
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id_(0),
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event_name_(event_name),
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tid_(tid),
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cpu_(cpu),
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mmap_addr_(nullptr),
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mmap_len_(0),
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mmap_metadata_page_(nullptr),
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mmap_data_buffer_(nullptr),
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mmap_data_buffer_size_(0),
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ioevent_ref_(nullptr),
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last_counter_value_(0) {}
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bool InnerReadCounter(PerfCounter* counter) const;
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const perf_event_attr attr_;
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int perf_event_fd_;
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mutable uint64_t id_;
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const std::string event_name_;
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pid_t tid_;
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int cpu_;
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void* mmap_addr_;
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size_t mmap_len_;
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perf_event_mmap_page* mmap_metadata_page_; // The first page of mmap_area.
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char* mmap_data_buffer_; // Starting from the second page of mmap_area,
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// containing records written by then kernel.
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size_t mmap_data_buffer_size_;
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IOEventRef ioevent_ref_;
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// Used by atrace to generate value difference between two ReadCounter() calls.
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uint64_t last_counter_value_;
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DISALLOW_COPY_AND_ASSIGN(EventFd);
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};
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bool IsEventAttrSupported(const perf_event_attr& attr);
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#endif // SIMPLE_PERF_EVENT_FD_H_
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