include/media/nbaio/NBLog.h - android_frameworks_av - Gitiles

 /*
  * Copyright (C) 2013 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.
  */

 // Non-blocking event logger intended for safe communication between processes via shared memory

 #ifndef ANDROID_MEDIA_NBLOG_H
 #define ANDROID_MEDIA_NBLOG_H

 #include <binder/IMemory.h>
 #include <utils/Mutex.h>
 #include <audio_utils/fifo.h>

 namespace android {

 class String8;

 class NBLog {

 public:

 class Writer;
 class Reader;

 private:

 enum Event {
     EVENT_RESERVED,
     EVENT_STRING,               // ASCII string, not NUL-terminated
     EVENT_TIMESTAMP,            // clock_gettime(CLOCK_MONOTONIC)
     EVENT_INTEGER,
     EVENT_FLOAT,
     EVENT_PID,
     EVENT_START_FMT,            // logFormat start event: entry includes format string, following
                                 // entries contain format arguments
     EVENT_END_FMT,              // end of logFormat argument list
 };

 // ---------------------------------------------------------------------------

 // representation of a single log entry in private memory
 struct Entry {
     Entry(Event event, const void *data, size_t length)
         : mEvent(event), mLength(length), mData(data) { }
     /*virtual*/ ~Entry() { }

     int     readAt(size_t offset) const;

 private:
     friend class Writer;
     Event       mEvent;     // event type
     uint8_t     mLength;    // length of additional data, 0 <= mLength <= kMaxLength
     const void *mData;      // event type-specific data
     static const size_t kMaxLength = 255;
 public:
     static const size_t kOverhead = 3;  // mEvent, mLength, mData[...], duplicate mLength
 };

 // representation of a single log entry in shared memory
 //  byte[0]             mEvent
 //  byte[1]             mLength
 //  byte[2]             mData[0]
 //  ...
 //  byte[2+i]           mData[i]
 //  ...
 //  byte[2+mLength-1]   mData[mLength-1]
 //  byte[2+mLength]     duplicate copy of mLength to permit reverse scan
 //  byte[3+mLength]     start of next log entry

     static void    appendInt(String8 *body, const void *data);
     static void    appendFloat(String8 *body, const void *data);
     static void    appendPID(String8 *body, const void *data, size_t length);
     static int     handleFormat(const char *fmt, size_t length, const uint8_t *data,
                                 String8 *timestamp, String8 *body);
     static void    appendTimestamp(String8 *body, const void *data);

 public:

 // Located in shared memory, must be POD.
 // Exactly one process must explicitly call the constructor or use placement new.
 // Since this is a POD, the destructor is empty and unnecessary to call it explicitly.
 struct Shared {
     Shared() /* mRear initialized via default constructor */ { }
     /*virtual*/ ~Shared() { }

     audio_utils_fifo_index  mRear;  // index one byte past the end of most recent Entry
     char    mBuffer[0];             // circular buffer for entries
 };

 public:

 // ---------------------------------------------------------------------------

 // FIXME Timeline was intended to wrap Writer and Reader, but isn't actually used yet.
 // For now it is just a namespace for sharedSize().
 class Timeline : public RefBase {
 public:
 #if 0
     Timeline(size_t size, void *shared = NULL);
     virtual ~Timeline();
 #endif

     // Input parameter 'size' is the desired size of the timeline in byte units.
     // Returns the size rounded up to a power-of-2, plus the constant size overhead for indices.
     static size_t sharedSize(size_t size);

 #if 0
 private:
     friend class    Writer;
     friend class    Reader;

     const size_t    mSize;      // circular buffer size in bytes, must be a power of 2
     bool            mOwn;       // whether I own the memory at mShared
     Shared* const   mShared;    // pointer to shared memory
 #endif
 };

 // ---------------------------------------------------------------------------

 // Writer is thread-safe with respect to Reader, but not with respect to multiple threads
 // calling Writer methods.  If you need multi-thread safety for writing, use LockedWriter.
 class Writer : public RefBase {
 public:
     Writer();                   // dummy nop implementation without shared memory

     // Input parameter 'size' is the desired size of the timeline in byte units.
     // The size of the shared memory must be at least Timeline::sharedSize(size).
     Writer(void *shared, size_t size);
     Writer(const sp<IMemory>& iMemory, size_t size);

     virtual ~Writer();

     virtual void    log(const char *string);
     virtual void    logf(const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
     virtual void    logvf(const char *fmt, va_list ap);
     virtual void    logTimestamp();
     virtual void    logTimestamp(const struct timespec &ts);
     virtual void    logInteger(const int x);
     virtual void    logFloat(const float x);
     virtual void    logPID();
     virtual void    logFormat(const char *fmt, ...);
     virtual void    logVFormat(const char *fmt, va_list ap);
     virtual void    logStart(const char *fmt);
     virtual void    logEnd();


     virtual bool    isEnabled() const;

     // return value for all of these is the previous isEnabled()
     virtual bool    setEnabled(bool enabled);   // but won't enable if no shared memory
             bool    enable()    { return setEnabled(true); }
             bool    disable()   { return setEnabled(false); }

     sp<IMemory>     getIMemory() const  { return mIMemory; }

 private:
     // 0 <= length <= kMaxLength
     void    log(Event event, const void *data, size_t length);
     void    log(const Entry *entry, bool trusted = false);

     Shared* const   mShared;    // raw pointer to shared memory
     sp<IMemory>     mIMemory;   // ref-counted version, initialized in constructor and then const
     audio_utils_fifo * const mFifo;                 // FIFO itself,
                                                     // non-NULL unless constructor fails
     audio_utils_fifo_writer * const mFifoWriter;    // used to write to FIFO,
                                                     // non-NULL unless dummy constructor used
     bool            mEnabled;   // whether to actually log

     // cached pid and process name to use in %p format specifier
     // total tag length is mPidTagSize and process name is not zero terminated
     char   *mPidTag;
     size_t  mPidTagSize;
 };

 // ---------------------------------------------------------------------------

 // Similar to Writer, but safe for multiple threads to call concurrently
 class LockedWriter : public Writer {
 public:
     LockedWriter();
     LockedWriter(void *shared, size_t size);

     virtual void    log(const char *string);
     virtual void    logf(const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
     virtual void    logvf(const char *fmt, va_list ap);
     virtual void    logTimestamp();
     virtual void    logTimestamp(const struct timespec &ts);
     virtual void    logInteger(const int x);
     virtual void    logFloat(const float x);
     virtual void    logPID();
     virtual void    logStart(const char *fmt);
     virtual void    logEnd();

     virtual bool    isEnabled() const;
     virtual bool    setEnabled(bool enabled);

 private:
     mutable Mutex   mLock;
 };

 // ---------------------------------------------------------------------------

 class Reader : public RefBase {
 public:

     // Input parameter 'size' is the desired size of the timeline in byte units.
     // The size of the shared memory must be at least Timeline::sharedSize(size).
     Reader(const void *shared, size_t size);
     Reader(const sp<IMemory>& iMemory, size_t size);

     virtual ~Reader();

     void    dump(int fd, size_t indent = 0);
     bool    isIMemory(const sp<IMemory>& iMemory) const;

 private:
     /*const*/ Shared* const mShared;    // raw pointer to shared memory, actually const but not
                                         // declared as const because audio_utils_fifo() constructor
     sp<IMemory> mIMemory;       // ref-counted version, assigned only in constructor
     int     mFd;                // file descriptor
     int     mIndent;            // indentation level
     audio_utils_fifo * const mFifo;                 // FIFO itself,
                                                     // non-NULL unless constructor fails
     audio_utils_fifo_reader * const mFifoReader;    // used to read from FIFO,
                                                     // non-NULL unless constructor fails

     void    dumpLine(const String8& timestamp, String8& body);

     static const size_t kSquashTimestamp = 5; // squash this many or more adjacent timestamps
 };

 };  // class NBLog

 }   // namespace android

 #endif  // ANDROID_MEDIA_NBLOG_H
	/*
	* Copyright (C) 2013 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.
	*/

	// Non-blocking event logger intended for safe communication between processes via shared memory

	#ifndef ANDROID_MEDIA_NBLOG_H
	#define ANDROID_MEDIA_NBLOG_H

	#include <binder/IMemory.h>
	#include <utils/Mutex.h>
	#include <audio_utils/fifo.h>

	namespace android {

	class String8;

	class NBLog {

	public:

	class Writer;
	class Reader;

	private:

	enum Event {
	EVENT_RESERVED,
	EVENT_STRING, // ASCII string, not NUL-terminated
	EVENT_TIMESTAMP, // clock_gettime(CLOCK_MONOTONIC)
	EVENT_INTEGER,
	EVENT_FLOAT,
	EVENT_PID,
	EVENT_START_FMT, // logFormat start event: entry includes format string, following
	// entries contain format arguments
	EVENT_END_FMT, // end of logFormat argument list
	};

	// ---------------------------------------------------------------------------

	// representation of a single log entry in private memory
	struct Entry {
	Entry(Event event, const void *data, size_t length)
	: mEvent(event), mLength(length), mData(data) { }
	/virtual/ ~Entry() { }

	int readAt(size_t offset) const;

	private:
	friend class Writer;
	Event mEvent; // event type
	uint8_t mLength; // length of additional data, 0 <= mLength <= kMaxLength
	const void *mData; // event type-specific data
	static const size_t kMaxLength = 255;
	public:
	static const size_t kOverhead = 3; // mEvent, mLength, mData[...], duplicate mLength
	};

	// representation of a single log entry in shared memory
	// byte[0] mEvent
	// byte[1] mLength
	// byte[2] mData[0]
	// ...
	// byte[2+i] mData[i]
	// ...
	// byte[2+mLength-1] mData[mLength-1]
	// byte[2+mLength] duplicate copy of mLength to permit reverse scan
	// byte[3+mLength] start of next log entry

	static void appendInt(String8 body, const void data);
	static void appendFloat(String8 body, const void data);
	static void appendPID(String8 body, const void data, size_t length);
	static int handleFormat(const char fmt, size_t length, const uint8_t data,
	String8 timestamp, String8 body);
	static void appendTimestamp(String8 body, const void data);

	public:

	// Located in shared memory, must be POD.
	// Exactly one process must explicitly call the constructor or use placement new.
	// Since this is a POD, the destructor is empty and unnecessary to call it explicitly.
	struct Shared {
	Shared() /* mRear initialized via default constructor */ { }
	/virtual/ ~Shared() { }

	audio_utils_fifo_index mRear; // index one byte past the end of most recent Entry
	char mBuffer[0]; // circular buffer for entries
	};

	public:

	// ---------------------------------------------------------------------------

	// FIXME Timeline was intended to wrap Writer and Reader, but isn't actually used yet.
	// For now it is just a namespace for sharedSize().
	class Timeline : public RefBase {
	public:
	#if 0
	Timeline(size_t size, void *shared = NULL);
	virtual ~Timeline();
	#endif

	// Input parameter 'size' is the desired size of the timeline in byte units.
	// Returns the size rounded up to a power-of-2, plus the constant size overhead for indices.
	static size_t sharedSize(size_t size);

	#if 0
	private:
	friend class Writer;
	friend class Reader;

	const size_t mSize; // circular buffer size in bytes, must be a power of 2
	bool mOwn; // whether I own the memory at mShared
	Shared* const mShared; // pointer to shared memory
	#endif
	};

	// ---------------------------------------------------------------------------

	// Writer is thread-safe with respect to Reader, but not with respect to multiple threads
	// calling Writer methods. If you need multi-thread safety for writing, use LockedWriter.
	class Writer : public RefBase {
	public:
	Writer(); // dummy nop implementation without shared memory

	// Input parameter 'size' is the desired size of the timeline in byte units.
	// The size of the shared memory must be at least Timeline::sharedSize(size).
	Writer(void *shared, size_t size);
	Writer(const sp<IMemory>& iMemory, size_t size);

	virtual ~Writer();

	virtual void log(const char *string);
	virtual void logf(const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
	virtual void logvf(const char *fmt, va_list ap);
	virtual void logTimestamp();
	virtual void logTimestamp(const struct timespec &ts);
	virtual void logInteger(const int x);
	virtual void logFloat(const float x);
	virtual void logPID();
	virtual void logFormat(const char *fmt, ...);
	virtual void logVFormat(const char *fmt, va_list ap);
	virtual void logStart(const char *fmt);
	virtual void logEnd();


	virtual bool isEnabled() const;

	// return value for all of these is the previous isEnabled()
	virtual bool setEnabled(bool enabled); // but won't enable if no shared memory
	bool enable() { return setEnabled(true); }
	bool disable() { return setEnabled(false); }

	sp<IMemory> getIMemory() const { return mIMemory; }

	private:
	// 0 <= length <= kMaxLength
	void log(Event event, const void *data, size_t length);
	void log(const Entry *entry, bool trusted = false);

	Shared* const mShared; // raw pointer to shared memory
	sp<IMemory> mIMemory; // ref-counted version, initialized in constructor and then const
	audio_utils_fifo * const mFifo; // FIFO itself,
	// non-NULL unless constructor fails
	audio_utils_fifo_writer * const mFifoWriter; // used to write to FIFO,
	// non-NULL unless dummy constructor used
	bool mEnabled; // whether to actually log

	// cached pid and process name to use in %p format specifier
	// total tag length is mPidTagSize and process name is not zero terminated
	char *mPidTag;
	size_t mPidTagSize;
	};

	// ---------------------------------------------------------------------------

	// Similar to Writer, but safe for multiple threads to call concurrently
	class LockedWriter : public Writer {
	public:
	LockedWriter();
	LockedWriter(void *shared, size_t size);

	virtual void log(const char *string);
	virtual void logf(const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
	virtual void logvf(const char *fmt, va_list ap);
	virtual void logTimestamp();
	virtual void logTimestamp(const struct timespec &ts);
	virtual void logInteger(const int x);
	virtual void logFloat(const float x);
	virtual void logPID();
	virtual void logStart(const char *fmt);
	virtual void logEnd();

	virtual bool isEnabled() const;
	virtual bool setEnabled(bool enabled);

	private:
	mutable Mutex mLock;
	};

	// ---------------------------------------------------------------------------

	class Reader : public RefBase {
	public:

	// Input parameter 'size' is the desired size of the timeline in byte units.
	// The size of the shared memory must be at least Timeline::sharedSize(size).
	Reader(const void *shared, size_t size);
	Reader(const sp<IMemory>& iMemory, size_t size);

	virtual ~Reader();

	void dump(int fd, size_t indent = 0);
	bool isIMemory(const sp<IMemory>& iMemory) const;

	private:
	/const/ Shared* const mShared; // raw pointer to shared memory, actually const but not
	// declared as const because audio_utils_fifo() constructor
	sp<IMemory> mIMemory; // ref-counted version, assigned only in constructor
	int mFd; // file descriptor
	int mIndent; // indentation level
	audio_utils_fifo * const mFifo; // FIFO itself,
	// non-NULL unless constructor fails
	audio_utils_fifo_reader * const mFifoReader; // used to read from FIFO,
	// non-NULL unless constructor fails

	void dumpLine(const String8& timestamp, String8& body);

	static const size_t kSquashTimestamp = 5; // squash this many or more adjacent timestamps
	};

	}; // class NBLog

	} // namespace android

	#endif // ANDROID_MEDIA_NBLOG_H