EventLog.c

/* -----------------------------------------------------------------------------
 *
 * (c) The GHC Team, 2008-2009
 *
 * Support for fast binary event logging.
 *
 * ---------------------------------------------------------------------------*/

#include "PosixSource.h"
#include "Rts.h"

#ifdef TRACING

#include "Trace.h"
#include "Capability.h"
#include "Trace.h"
#include "RtsUtils.h"
#include "Stats.h"
#include "EventLog.h"

#include <string.h> 
#include <stdio.h>

static char *event_log_filename = NULL;

// File for logging events
FILE *event_log_file = NULL;

#define EVENT_LOG_SIZE 2 * (1024 * 1024) // 2MB

static int flushCount;

// Struct for record keeping of buffer to store event types and events.
typedef struct _EventsBuf {
  StgInt8 *begin;
  StgInt8 *pos;
  StgInt8 *marker;
  StgWord64 size;
  EventCapNo capno; // which capability this buffer belongs to, or -1
} EventsBuf;

EventsBuf *capEventBuf; // one EventsBuf for each Capability

EventsBuf eventBuf; // an EventsBuf not associated with any Capability
#ifdef THREADED_RTS
Mutex eventBufMutex; // protected by this mutex
#endif

char *EventDesc[] = {
  [EVENT_CREATE_THREAD]       = "Create thread",
  [EVENT_RUN_THREAD]          = "Run thread",
  [EVENT_STOP_THREAD]         = "Stop thread",
  [EVENT_THREAD_RUNNABLE]     = "Thread runnable",
  [EVENT_MIGRATE_THREAD]      = "Migrate thread",
  [EVENT_RUN_SPARK]           = "Run spark",
  [EVENT_STEAL_SPARK]         = "Steal spark",
  [EVENT_SHUTDOWN]            = "Shutdown",
  [EVENT_THREAD_WAKEUP]       = "Wakeup thread",
  [EVENT_GC_START]            = "Starting GC",
  [EVENT_GC_END]              = "Finished GC",
  [EVENT_REQUEST_SEQ_GC]      = "Request sequential GC",
  [EVENT_REQUEST_PAR_GC]      = "Request parallel GC",
  [EVENT_CREATE_SPARK_THREAD] = "Create spark thread",
  [EVENT_LOG_MSG]             = "Log message",
  [EVENT_STARTUP]             = "Startup",
  [EVENT_BLOCK_MARKER]        = "Block marker"
};

// Event type. 

typedef struct _EventType {
  EventTypeNum etNum;  // Event Type number.
  nat   size;     // size of the payload in bytes
  char *desc;     // Description
} EventType;

EventType eventTypes[NUM_EVENT_TAGS];

static void initEventsBuf(EventsBuf* eb, StgWord64 size, EventCapNo capno);
static void resetEventsBuf(EventsBuf* eb);
static void printAndClearEventBuf (EventsBuf *eventsBuf);

static void postEventType(EventsBuf *eb, EventType *et);

static void postLogMsg(EventsBuf *eb, char *msg, va_list ap);

static void postBlockMarker(EventsBuf *eb);
static void closeBlockMarker(EventsBuf *ebuf);

static StgBool hasRoomForEvent(EventsBuf *eb, EventTypeNum eNum);
static StgBool hasRoomForVariableEvent(EventsBuf *eb, nat payload_bytes);

static inline void postWord8(EventsBuf *eb, StgWord8 i)
{
    *(eb->pos++) = i; 
}

static inline void postWord16(EventsBuf *eb, StgWord16 i)
{
    postWord8(eb, (StgWord8)(i >> 8));
    postWord8(eb, (StgWord8)i);
}

static inline void postWord32(EventsBuf *eb, StgWord32 i)
{
    postWord16(eb, (StgWord16)(i >> 16));
    postWord16(eb, (StgWord16)i);
}

static inline void postWord64(EventsBuf *eb, StgWord64 i)
{
    postWord32(eb, (StgWord32)(i >> 32));
    postWord32(eb, (StgWord32)i);
}

static inline void postBuf(EventsBuf *eb, StgWord8 *buf, nat size)
{
    memcpy(eb->pos, buf, size);
    eb->pos += size;
}

static inline StgWord64 time_ns(void)
{ return stat_getElapsedTime() * (1000000000LL/TICKS_PER_SECOND); }

static inline void postEventTypeNum(EventsBuf *eb, EventTypeNum etNum)
{ postWord16(eb, etNum); }

static inline void postTimestamp(EventsBuf *eb)
{ postWord64(eb, time_ns()); }

static inline void postThreadID(EventsBuf *eb, EventThreadID id)
{ postWord32(eb,id); }

static inline void postCapNo(EventsBuf *eb, EventCapNo no)
{ postWord16(eb,no); }

static inline void postPayloadSize(EventsBuf *eb, EventPayloadSize size)
{ postWord16(eb,size); }

static inline void postEventHeader(EventsBuf *eb, EventTypeNum type)
{
    postEventTypeNum(eb, type);
    postTimestamp(eb);
}    

static inline void postInt8(EventsBuf *eb, StgInt8 i)
{ postWord8(eb, (StgWord8)i); }

static inline void postInt16(EventsBuf *eb, StgInt16 i)
{ postWord16(eb, (StgWord16)i); }

static inline void postInt32(EventsBuf *eb, StgInt32 i)
{ postWord32(eb, (StgWord32)i); }

static inline void postInt64(EventsBuf *eb, StgInt64 i)
{ postWord64(eb, (StgWord64)i); }


void
initEventLogging(void)
{
    StgWord8 t, c;
    nat n_caps;

    event_log_filename = stgMallocBytes(strlen(prog_name) + 10,
                                        "initEventLogging");

    if (sizeof(EventDesc) / sizeof(char*) != NUM_EVENT_TAGS) {
        barf("EventDesc array has the wrong number of elements");
    }
  
    sprintf(event_log_filename, "%s.eventlog", prog_name);
    
    /* Open event log file for writing. */
    if ((event_log_file = fopen(event_log_filename, "wb")) == NULL) {
        sysErrorBelch("initEventLogging: can't open %s", event_log_filename);
        stg_exit(EXIT_FAILURE);    
    }

    /* 
     * Allocate buffer(s) to store events.
     * Create buffer large enough for the header begin marker, all event
     * types, and header end marker to prevent checking if buffer has room
     * for each of these steps, and remove the need to flush the buffer to
     * disk during initialization.
     *
     * Use a single buffer to store the header with event types, then flush 
     * the buffer so all buffers are empty for writing events.
     */
#ifdef THREADED_RTS
    // XXX n_capabilities hasn't been initislised yet
    n_caps = RtsFlags.ParFlags.nNodes;
#else
    n_caps = 1;
#endif
    capEventBuf = stgMallocBytes(n_caps * sizeof(EventsBuf),"initEventLogging");

    for (c = 0; c < n_caps; ++c) {
        // Init buffer for events.
        initEventsBuf(&capEventBuf[c], EVENT_LOG_SIZE, c);
    }
    initEventsBuf(&eventBuf, EVENT_LOG_SIZE, (EventCapNo)(-1));

    // Write in buffer: the header begin marker.
    postInt32(&eventBuf, EVENT_HEADER_BEGIN);

    // Mark beginning of event types in the header.
    postInt32(&eventBuf, EVENT_HET_BEGIN);
    for (t = 0; t < NUM_EVENT_TAGS; ++t) {

        eventTypes[t].etNum = t;
        eventTypes[t].desc = EventDesc[t];

        switch (t) {
        case EVENT_CREATE_THREAD:   // (cap, thread)
        case EVENT_RUN_THREAD:      // (cap, thread)
        case EVENT_THREAD_RUNNABLE: // (cap, thread)
        case EVENT_RUN_SPARK:       // (cap, thread)
        case EVENT_CREATE_SPARK_THREAD: // (cap, spark_thread)
            eventTypes[t].size = sizeof(EventThreadID);
            break;

        case EVENT_MIGRATE_THREAD:  // (cap, thread, new_cap)
        case EVENT_STEAL_SPARK:     // (cap, thread, victim_cap)
        case EVENT_THREAD_WAKEUP:   // (cap, thread, other_cap)
            eventTypes[t].size =
                sizeof(EventThreadID) + sizeof(EventCapNo);
            break;

        case EVENT_STOP_THREAD:     // (cap, thread, status)
            eventTypes[t].size =
                sizeof(EventThreadID) + sizeof(StgWord16);
            break;

        case EVENT_SHUTDOWN:        // (cap)
        case EVENT_REQUEST_SEQ_GC:  // (cap)
        case EVENT_REQUEST_PAR_GC:  // (cap)
        case EVENT_GC_START:        // (cap)
        case EVENT_GC_END:          // (cap)
        case EVENT_STARTUP:
            eventTypes[t].size = 0;
            break;

        case EVENT_LOG_MSG:          // (msg)
            eventTypes[t].size = 0xffff;
            break;

        case EVENT_BLOCK_MARKER:
            eventTypes[t].size = sizeof(StgWord32) + sizeof(EventTimestamp) + 
                sizeof(EventCapNo);
            break;

        default:
            continue; /* ignore deprecated events */
        }

        // Write in buffer: the start event type.
        postEventType(&eventBuf, &eventTypes[t]);
    }

    // Mark end of event types in the header.
    postInt32(&eventBuf, EVENT_HET_END);
    
    // Write in buffer: the header end marker.
    postInt32(&eventBuf, EVENT_HEADER_END);
    
    // Prepare event buffer for events (data).
    postInt32(&eventBuf, EVENT_DATA_BEGIN);
    
    // Post a STARTUP event with the number of capabilities
    postEventHeader(&eventBuf, EVENT_STARTUP);
    postCapNo(&eventBuf, n_caps);

    // Flush capEventBuf with header.
    /*
     * Flush header and data begin marker to the file, thus preparing the
     * file to have events written to it.
     */
    printAndClearEventBuf(&eventBuf);

    for (c = 0; c < n_caps; ++c) {
        postBlockMarker(&capEventBuf[c]);
    }
}

void
endEventLogging(void)
{
    nat c;

    // Flush all events remaining in the buffers.
    for (c = 0; c < n_capabilities; ++c) {
        printAndClearEventBuf(&capEventBuf[c]);
    }
    printAndClearEventBuf(&eventBuf);
    resetEventsBuf(&eventBuf); // we don't want the block marker

    // Mark end of events (data).
    postEventTypeNum(&eventBuf, EVENT_DATA_END);

    // Flush the end of data marker.
    printAndClearEventBuf(&eventBuf);

    if (event_log_file != NULL) {
        fclose(event_log_file);
    }
}

void 
freeEventLogging(void)
{
    StgWord8 c;
    
    // Free events buffer.
    for (c = 0; c < n_capabilities; ++c) {
        if (capEventBuf[c].begin != NULL) 
            stgFree(capEventBuf[c].begin);
    }
    if (capEventBuf != NULL)  {
        stgFree(capEventBuf);
    }
    if (event_log_filename != NULL) {
        stgFree(event_log_filename);
    }
}

/*
 * Post an event message to the capability's eventlog buffer.
 * If the buffer is full, prints out the buffer and clears it.
 */
void
postSchedEvent (Capability *cap, 
                EventTypeNum tag, 
                StgThreadID thread, 
                StgWord64 other)
{
    EventsBuf *eb;

    eb = &capEventBuf[cap->no];

    if (!hasRoomForEvent(eb, tag)) {
        // Flush event buffer to make room for new event.
        printAndClearEventBuf(eb);
    }
    
    postEventHeader(eb, tag);

    switch (tag) {
    case EVENT_CREATE_THREAD:   // (cap, thread)
    case EVENT_RUN_THREAD:      // (cap, thread)
    case EVENT_THREAD_RUNNABLE: // (cap, thread)
    case EVENT_RUN_SPARK:       // (cap, thread)
    {
        postThreadID(eb,thread);
        break;
    }

    case EVENT_CREATE_SPARK_THREAD: // (cap, spark_thread)
    {
        postThreadID(eb,other /* spark_thread */);
        break;
    }

    case EVENT_MIGRATE_THREAD:  // (cap, thread, new_cap)
    case EVENT_STEAL_SPARK:     // (cap, thread, victim_cap)
    case EVENT_THREAD_WAKEUP:   // (cap, thread, other_cap)
    {
        postThreadID(eb,thread);
        postCapNo(eb,other /* new_cap | victim_cap | other_cap */);
        break;
   }

    case EVENT_STOP_THREAD:     // (cap, thread, status)
    {
        postThreadID(eb,thread);
        postWord16(eb,other /* status */);
        break;
    }

    case EVENT_SHUTDOWN:        // (cap)
    case EVENT_REQUEST_SEQ_GC:  // (cap)
    case EVENT_REQUEST_PAR_GC:  // (cap)
    case EVENT_GC_START:        // (cap)
    case EVENT_GC_END:          // (cap)
    {
        break;
    }

    default:
        barf("postEvent: unknown event tag %d", tag);
    }
}

#define BUF 512

void postLogMsg(EventsBuf *eb, char *msg, va_list ap)
{
    char buf[BUF];
    nat size;

    size = vsnprintf(buf,BUF,msg,ap);
    if (size > BUF) {
        buf[BUF-1] = '\0';
        size = BUF;
    }

    if (!hasRoomForVariableEvent(eb, size)) {
        // Flush event buffer to make room for new event.
        printAndClearEventBuf(eb);
    }

    postEventHeader(eb, EVENT_LOG_MSG);
    postPayloadSize(eb, size);
    postBuf(eb,(StgWord8*)buf,size);
}

void postMsg(char *msg, va_list ap)
{
    ACQUIRE_LOCK(&eventBufMutex);
    postLogMsg(&eventBuf, msg, ap);
    RELEASE_LOCK(&eventBufMutex);
}

void postCapMsg(Capability *cap, char *msg, va_list ap)
{
    postLogMsg(&capEventBuf[cap->no], msg, ap);
}

void closeBlockMarker (EventsBuf *ebuf)
{
    StgInt8* save_pos;

    if (ebuf->marker)
    {
        // (type:16, time:64, size:32, end_time:64)

        save_pos = ebuf->pos;
        ebuf->pos = ebuf->marker + sizeof(EventTypeNum) +
                    sizeof(EventTimestamp);
        postWord32(ebuf, save_pos - ebuf->marker);
        postTimestamp(ebuf);
        ebuf->pos = save_pos;
        ebuf->marker = NULL;
    }
}


void postBlockMarker (EventsBuf *eb)
{
    if (!hasRoomForEvent(eb, EVENT_BLOCK_MARKER)) {
        printAndClearEventBuf(eb);
    }

    closeBlockMarker(eb);

    eb->marker = eb->pos;
    postEventHeader(eb, EVENT_BLOCK_MARKER);
    postWord32(eb,0); // these get filled in later by closeBlockMarker();
    postWord64(eb,0);
    postCapNo(eb, eb->capno);
}

void printAndClearEventBuf (EventsBuf *ebuf)
{
    StgWord64 numBytes = 0, written = 0;

    closeBlockMarker(ebuf);

    if (ebuf->begin != NULL && ebuf->pos != ebuf->begin)
    {
        numBytes = ebuf->pos - ebuf->begin;
        
        written = fwrite(ebuf->begin, 1, numBytes, event_log_file);
        if (written != numBytes) {
            debugBelch(
                "printAndClearEventLog: fwrite() failed, written=%" FMT_Word64
                " doesn't match numBytes=%" FMT_Word64, written, numBytes);
            return;
        }
        
        resetEventsBuf(ebuf);
        flushCount++;

        postBlockMarker(ebuf);
    }
}

void initEventsBuf(EventsBuf* eb, StgWord64 size, EventCapNo capno)
{
    eb->begin = eb->pos = stgMallocBytes(size, "initEventsBuf");
    eb->size = size;
    eb->marker = NULL;
    eb->capno = capno;
}

void resetEventsBuf(EventsBuf* eb)
{
    eb->pos = eb->begin;
    eb->marker = NULL;
}

StgBool hasRoomForEvent(EventsBuf *eb, EventTypeNum eNum)
{
  nat size;

  size = sizeof(EventTypeNum) + sizeof(EventTimestamp) + eventTypes[eNum].size;

  if (eb->pos + size > eb->begin + eb->size) {
      return 0; // Not enough space.
  } else  {
      return 1; // Buf has enough space for the event.
  }
}

StgBool hasRoomForVariableEvent(EventsBuf *eb, nat payload_bytes)
{
  nat size;

  size = sizeof(EventTypeNum) + sizeof(EventTimestamp) +
      sizeof(EventPayloadSize) + payload_bytes;

  if (eb->pos + size > eb->begin + eb->size) {
      return 0; // Not enough space.
  } else  {
      return 1; // Buf has enough space for the event.
  }
}    

void postEventType(EventsBuf *eb, EventType *et)
{
    StgWord8 d;
    nat desclen;

    postInt32(eb, EVENT_ET_BEGIN);
    postEventTypeNum(eb, et->etNum);
    postWord16(eb, (StgWord16)et->size);
    desclen = strlen(et->desc);
    postWord32(eb, desclen);
    for (d = 0; d < desclen; ++d) {
        postInt8(eb, (StgInt8)et->desc[d]);
    }
    postWord32(eb, 0); // no extensions yet
    postInt32(eb, EVENT_ET_END);
}

#endif /* TRACING */