271 lines
9.6 KiB
C++
271 lines
9.6 KiB
C++
/*
|
|
* Copyright (C) 2010 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 UTILS_LOOPER_H
|
|
#define UTILS_LOOPER_H
|
|
|
|
#include <utils/threads.h>
|
|
#include <utils/RefBase.h>
|
|
#include <utils/KeyedVector.h>
|
|
#include <utils/Timers.h>
|
|
|
|
#include <android/looper.h>
|
|
|
|
// When defined, uses epoll_wait() for polling, otherwise uses poll().
|
|
#define LOOPER_USES_EPOLL
|
|
|
|
// When defined, logs performance statistics for tuning and debugging purposes.
|
|
//#define LOOPER_STATISTICS
|
|
|
|
#ifdef LOOPER_USES_EPOLL
|
|
#include <sys/epoll.h>
|
|
#else
|
|
#include <sys/poll.h>
|
|
#endif
|
|
|
|
/*
|
|
* Declare a concrete type for the NDK's looper forward declaration.
|
|
*/
|
|
struct ALooper {
|
|
};
|
|
|
|
namespace android {
|
|
|
|
/**
|
|
* A polling loop that supports monitoring file descriptor events, optionally
|
|
* using callbacks. The implementation uses epoll() internally.
|
|
*
|
|
* A looper can be associated with a thread although there is no requirement that it must be.
|
|
*/
|
|
class Looper : public ALooper, public RefBase {
|
|
protected:
|
|
virtual ~Looper();
|
|
|
|
public:
|
|
/**
|
|
* Creates a looper.
|
|
*
|
|
* If allowNonCallbaks is true, the looper will allow file descriptors to be
|
|
* registered without associated callbacks. This assumes that the caller of
|
|
* pollOnce() is prepared to handle callback-less events itself.
|
|
*/
|
|
Looper(bool allowNonCallbacks);
|
|
|
|
/**
|
|
* Returns whether this looper instance allows the registration of file descriptors
|
|
* using identifiers instead of callbacks.
|
|
*/
|
|
bool getAllowNonCallbacks() const;
|
|
|
|
/**
|
|
* Waits for events to be available, with optional timeout in milliseconds.
|
|
* Invokes callbacks for all file descriptors on which an event occurred.
|
|
*
|
|
* If the timeout is zero, returns immediately without blocking.
|
|
* If the timeout is negative, waits indefinitely until an event appears.
|
|
*
|
|
* Returns ALOOPER_POLL_WAKE if the poll was awoken using wake() before
|
|
* the timeout expired and no callbacks were invoked and no other file
|
|
* descriptors were ready.
|
|
*
|
|
* Returns ALOOPER_POLL_CALLBACK if one or more callbacks were invoked.
|
|
*
|
|
* Returns ALOOPER_POLL_TIMEOUT if there was no data before the given
|
|
* timeout expired.
|
|
*
|
|
* Returns ALOOPER_POLL_ERROR if an error occurred.
|
|
*
|
|
* Returns a value >= 0 containing an identifier if its file descriptor has data
|
|
* and it has no callback function (requiring the caller here to handle it).
|
|
* In this (and only this) case outFd, outEvents and outData will contain the poll
|
|
* events and data associated with the fd, otherwise they will be set to NULL.
|
|
*
|
|
* This method does not return until it has finished invoking the appropriate callbacks
|
|
* for all file descriptors that were signalled.
|
|
*/
|
|
int pollOnce(int timeoutMillis, int* outFd, int* outEvents, void** outData);
|
|
inline int pollOnce(int timeoutMillis) {
|
|
return pollOnce(timeoutMillis, NULL, NULL, NULL);
|
|
}
|
|
|
|
/**
|
|
* Like pollOnce(), but performs all pending callbacks until all
|
|
* data has been consumed or a file descriptor is available with no callback.
|
|
* This function will never return ALOOPER_POLL_CALLBACK.
|
|
*/
|
|
int pollAll(int timeoutMillis, int* outFd, int* outEvents, void** outData);
|
|
inline int pollAll(int timeoutMillis) {
|
|
return pollAll(timeoutMillis, NULL, NULL, NULL);
|
|
}
|
|
|
|
/**
|
|
* Wakes the poll asynchronously.
|
|
*
|
|
* This method can be called on any thread.
|
|
* This method returns immediately.
|
|
*/
|
|
void wake();
|
|
|
|
/**
|
|
* Adds a new file descriptor to be polled by the looper.
|
|
* If the same file descriptor was previously added, it is replaced.
|
|
*
|
|
* "fd" is the file descriptor to be added.
|
|
* "ident" is an identifier for this event, which is returned from ALooper_pollOnce().
|
|
* The identifier must be >= 0, or ALOOPER_POLL_CALLBACK if providing a non-NULL callback.
|
|
* "events" are the poll events to wake up on. Typically this is ALOOPER_EVENT_INPUT.
|
|
* "callback" is the function to call when there is an event on the file descriptor.
|
|
* "data" is a private data pointer to supply to the callback.
|
|
*
|
|
* There are two main uses of this function:
|
|
*
|
|
* (1) If "callback" is non-NULL, then this function will be called when there is
|
|
* data on the file descriptor. It should execute any events it has pending,
|
|
* appropriately reading from the file descriptor. The 'ident' is ignored in this case.
|
|
*
|
|
* (2) If "callback" is NULL, the 'ident' will be returned by ALooper_pollOnce
|
|
* when its file descriptor has data available, requiring the caller to take
|
|
* care of processing it.
|
|
*
|
|
* Returns 1 if the file descriptor was added, 0 if the arguments were invalid.
|
|
*
|
|
* This method can be called on any thread.
|
|
* This method may block briefly if it needs to wake the poll.
|
|
*/
|
|
int addFd(int fd, int ident, int events, ALooper_callbackFunc callback, void* data);
|
|
|
|
/**
|
|
* Removes a previously added file descriptor from the looper.
|
|
*
|
|
* When this method returns, it is safe to close the file descriptor since the looper
|
|
* will no longer have a reference to it. However, it is possible for the callback to
|
|
* already be running or for it to run one last time if the file descriptor was already
|
|
* signalled. Calling code is responsible for ensuring that this case is safely handled.
|
|
* For example, if the callback takes care of removing itself during its own execution either
|
|
* by returning 0 or by calling this method, then it can be guaranteed to not be invoked
|
|
* again at any later time unless registered anew.
|
|
*
|
|
* Returns 1 if the file descriptor was removed, 0 if none was previously registered.
|
|
*
|
|
* This method can be called on any thread.
|
|
* This method may block briefly if it needs to wake the poll.
|
|
*/
|
|
int removeFd(int fd);
|
|
|
|
/**
|
|
* Prepares a looper associated with the calling thread, and returns it.
|
|
* If the thread already has a looper, it is returned. Otherwise, a new
|
|
* one is created, associated with the thread, and returned.
|
|
*
|
|
* The opts may be ALOOPER_PREPARE_ALLOW_NON_CALLBACKS or 0.
|
|
*/
|
|
static sp<Looper> prepare(int opts);
|
|
|
|
/**
|
|
* Sets the given looper to be associated with the calling thread.
|
|
* If another looper is already associated with the thread, it is replaced.
|
|
*
|
|
* If "looper" is NULL, removes the currently associated looper.
|
|
*/
|
|
static void setForThread(const sp<Looper>& looper);
|
|
|
|
/**
|
|
* Returns the looper associated with the calling thread, or NULL if
|
|
* there is not one.
|
|
*/
|
|
static sp<Looper> getForThread();
|
|
|
|
private:
|
|
struct Request {
|
|
int fd;
|
|
int ident;
|
|
ALooper_callbackFunc callback;
|
|
void* data;
|
|
};
|
|
|
|
struct Response {
|
|
int events;
|
|
Request request;
|
|
};
|
|
|
|
const bool mAllowNonCallbacks; // immutable
|
|
|
|
int mWakeReadPipeFd; // immutable
|
|
int mWakeWritePipeFd; // immutable
|
|
Mutex mLock;
|
|
|
|
#ifdef LOOPER_USES_EPOLL
|
|
int mEpollFd; // immutable
|
|
|
|
// Locked list of file descriptor monitoring requests.
|
|
KeyedVector<int, Request> mRequests; // guarded by mLock
|
|
#else
|
|
// The lock guards state used to track whether there is a poll() in progress and whether
|
|
// there are any other threads waiting in wakeAndLock(). The condition variables
|
|
// are used to transfer control among these threads such that all waiters are
|
|
// serviced before a new poll can begin.
|
|
// The wakeAndLock() method increments mWaiters, wakes the poll, blocks on mAwake
|
|
// until mPolling becomes false, then decrements mWaiters again.
|
|
// The poll() method blocks on mResume until mWaiters becomes 0, then sets
|
|
// mPolling to true, blocks until the poll completes, then resets mPolling to false
|
|
// and signals mResume if there are waiters.
|
|
bool mPolling; // guarded by mLock
|
|
uint32_t mWaiters; // guarded by mLock
|
|
Condition mAwake; // guarded by mLock
|
|
Condition mResume; // guarded by mLock
|
|
|
|
Vector<struct pollfd> mRequestedFds; // must hold mLock and mPolling must be false to modify
|
|
Vector<Request> mRequests; // must hold mLock and mPolling must be false to modify
|
|
|
|
ssize_t getRequestIndexLocked(int fd);
|
|
void wakeAndLock();
|
|
#endif
|
|
|
|
#ifdef LOOPER_STATISTICS
|
|
static const int SAMPLED_WAKE_CYCLES_TO_AGGREGATE = 100;
|
|
static const int SAMPLED_POLLS_TO_AGGREGATE = 1000;
|
|
|
|
nsecs_t mPendingWakeTime;
|
|
int mPendingWakeCount;
|
|
|
|
int mSampledWakeCycles;
|
|
int mSampledWakeCountSum;
|
|
nsecs_t mSampledWakeLatencySum;
|
|
|
|
int mSampledPolls;
|
|
int mSampledZeroPollCount;
|
|
int mSampledZeroPollLatencySum;
|
|
int mSampledTimeoutPollCount;
|
|
int mSampledTimeoutPollLatencySum;
|
|
#endif
|
|
|
|
// This state is only used privately by pollOnce and does not require a lock since
|
|
// it runs on a single thread.
|
|
Vector<Response> mResponses;
|
|
size_t mResponseIndex;
|
|
|
|
int pollInner(int timeoutMillis);
|
|
void awoken();
|
|
void pushResponse(int events, const Request& request);
|
|
|
|
static void initTLSKey();
|
|
static void threadDestructor(void *st);
|
|
};
|
|
|
|
} // namespace android
|
|
|
|
#endif // UTILS_LOOPER_H
|