/*

 * Copyright (c) 2020 Red Hat, Inc.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 * 

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 * 

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA. 

 *

 * $Id: //eng/vdo-releases/aluminum/src/c++/vdo/kernel/ktrace.h#1 $

 */

#ifndef KTRACE_H

#define KTRACE_H

#include <linux/device-mapper.h>

#include "common.h"

#include "trace.h"

struct kernelLayer;

struct kvio;

// Implement event sampling once per N.

typedef struct {

  unsigned int interval;

  unsigned int tick;

  spinlock_t   lock;

} SampleCounter;

/**

 * Flag indicating whether newly created VDO devices should record trace info.

 **/

extern bool traceRecording;

/**

 * Updates the counter state and returns true once each time the

 * sampling interval is reached.

 *

 * @param counter    The sampling counter info

 *

 * @return whether to do sampling on this invocation

 **/

bool sampleThisOne(SampleCounter *counter);

/**

 * Initialize trace data in the KernelLayer

 *

 * @param layer  The KernelLayer

 *

 * @return VDO_SUCCESS, or an error code

 **/

int traceKernelLayerInit(struct kernelLayer *layer);

/**

 * Initialize the mutex used when logging latency tracing data.

 **/

void initializeTraceLoggingOnce(void);

/**

 * Allocate a trace buffer

 *

 * @param layer         The KernelLayer

 * @param tracePointer  The trace buffer is returned here

 *

 * @return VDO_SUCCESS or an error code

 **/

int allocTraceFromPool(struct kernelLayer *layer, Trace **tracePointer);

/**

 * Free a trace buffer

 *

 * @param layer  The KernelLayer

 * @param trace  The trace buffer

 **/

void freeTraceToPool(struct kernelLayer *layer, Trace *trace);

/**

 * Log the trace at kvio freeing time

 *

 * @param kvio  The kvio structure

 **/

void logKvioTrace(struct kvio *kvio);

#endif /* KTRACE_H */