stasis-aries-wal/src/lladd/bufferManager.c

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---*/
/*******************************
 * $Id$
 *
 * implementation of the page buffer
 * *************************************************/

#include <config.h>
#include <lladd/common.h>
#include <latches.h>
#include <assert.h>
#include <lladd/bufferManager.h>
#include "blobManager.h"
#include <lladd/pageCache.h>

#include "page.h"
#include "pageFile.h"

/**
   Invariant: This lock should be held while updating lastFreepage, or
   while performing any operation that may decrease the amount of
   freespace in the page that lastFreepage refers to.  

   Since pageCompact and pageDeRalloc may only increase this value,
   they do not need to hold this lock.  Since bufferManager is the
   only place where pageRalloc is called, pageRalloc does not obtain
   this lock.
*/

static pthread_mutex_t lastFreepage_mutex;
pthread_mutex_t add_pending_mutex;

static unsigned int lastFreepage = 0;

/**
 * @param pageid ID of the page you want to load
 * @return fully formed Page type
 * @return page with -1 ID if page not found
 */
Page * loadPage(int pageid);

pthread_cond_t addPendingOK;

int bufInit() {

  /*	stable = NULL; */
	pageInit();
	openPageFile();
	pageCacheInit();
	openBlobStore();

	lastFreepage = 0;
	pthread_mutex_init(&lastFreepage_mutex , NULL);
	pthread_cond_init(&addPendingOK, NULL);
	pthread_mutex_init(&add_pending_mutex, NULL);


	return 0;
}

void bufDeinit() {

	closeBlobStore();
	pageCacheDeinit();
	closePageFile();

	return;
}
/**
    Just close file descriptors, don't do any other clean up. (For
    testing.)
*/
void simulateBufferManagerCrash() {
  closeBlobStore();
  closePageFile();
}

/* ** No file I/O below this line. ** */

Page * loadPage (int pageid) {
  Page * p = loadPagePtr(pageid);
  assert (p->id == pageid);
  return  p; 
}

Page * lastRallocPage = 0;

/** @todo ralloc ignores it's xid parameter; change the interface? */
recordid ralloc(int xid, /*lsn_t lsn,*/ long size) {
  
  recordid ret;
  Page * p;
  
  /*  DEBUG("Rallocing record of size %ld\n", (long int)size); */
  
  assert(size < BLOB_THRESHOLD_SIZE || size == BLOB_SLOT);
  
  pthread_mutex_lock(&lastFreepage_mutex);
  
  while(freespace(p = loadPage(lastFreepage)) < size ) { unlock(p->loadlatch); lastFreepage++; }
  
  ret = pageRalloc(p, size);
    
  unlock(p->loadlatch);
  pthread_mutex_unlock(&lastFreepage_mutex);
  
  /*  DEBUG("alloced rid = {%d, %d, %ld}\n", ret.page, ret.slot, ret.size); */

  return ret;
}

void slotRalloc(int pageid, lsn_t lsn, recordid rid) {
  Page * loadedPage = loadPage(rid.page);
  pageSlotRalloc(loadedPage, lsn, rid);
  unlock(loadedPage->loadlatch);
}

long readLSN(int pageid) {
  Page *p;
  lsn_t lsn = pageReadLSN(p = loadPage(pageid));
  unlock(p->loadlatch);
  return lsn;
}

void writeRecord(int xid, lsn_t lsn, recordid rid, const void *dat) {

  Page *p;
  
  if(rid.size > BLOB_THRESHOLD_SIZE) {
    /*    DEBUG("Writing blob.\n"); */
    writeBlob(xid, lsn, rid, dat);

  } else {
    /*    DEBUG("Writing record.\n"); */
    p = loadPage(rid.page); /* loadPagePtr(rid.page); */
    assert( (p->id == rid.page) && (p->memAddr != NULL) );	
    /** @todo This assert should be here, but the tests are broken, so it causes bogus failures. */
    /*assert(pageReadLSN(*p) <= lsn);*/
    
    pageWriteRecord(xid, p, rid, lsn, dat);
    
    unlock(p->loadlatch);
    
  }
}

void readRecord(int xid, recordid rid, void *buf) {
  if(rid.size > BLOB_THRESHOLD_SIZE) {
    /*    DEBUG("Reading blob. xid = %d rid = { %d %d %ld } buf = %x\n", 
	  xid, rid.page, rid.slot, rid.size, (unsigned int)buf); */
    readBlob(xid, rid, buf);
  } else {
    Page * p = loadPage(rid.page);
    assert(rid.page == p->id); 
    /*    DEBUG("Reading record xid = %d rid = { %d %d %ld } buf = %x\n", 
	  xid, rid.page, rid.slot, rid.size, (unsigned int)buf); */
    pageReadRecord(xid, p, rid, buf);
    assert(rid.page == p->id); 
    unlock(p->loadlatch);
  }
}

int bufTransCommit(int xid, lsn_t lsn) {

  commitBlobs(xid);
  pageCommit(xid);

  return 0;
}

int bufTransAbort(int xid, lsn_t lsn) {

  abortBlobs(xid);  /* abortBlobs doesn't write any log entries, so it doesn't need the lsn. */
  pageAbort(xid);

  return 0;
}

void setSlotType(int pageid, int slot, int type) {
  Page * p = loadPage(pageid);
  pageSetSlotType(p, slot, type);
  unlock(p->loadlatch);
}

/** 
    Inform bufferManager that a new event (such as an update) will be
    performed on page pageid.  This function may not be called on a
    page after finalize() has been called on that page, and each call
    to this function must be followed by a corresponding call to
    removePendingEvent.

    This function is called by the logger when CLR or UPDATE records
    are written.
    
    @see finalize, removePendingEvent

*/
void addPendingEvent(int pageid){
  
  Page * p;

  p = loadPage(pageid);

  pthread_mutex_lock(&add_pending_mutex);

  while(p->waiting) {

    pthread_mutex_unlock(&add_pending_mutex);

    unlock(p->loadlatch);
    DEBUG("B");
    pthread_mutex_lock(&add_pending_mutex);
    pthread_cond_wait(&addPendingOK, &add_pending_mutex);
    pthread_mutex_unlock(&add_pending_mutex);

    p = loadPage(pageid);

    pthread_mutex_lock(&add_pending_mutex);

  }

  p->pending++;

  pthread_mutex_unlock(&add_pending_mutex);

  unlock(p->loadlatch);


}

/**
   
   Because updates to a page might not happen in order, we need to
   make sure that we've applied all updates to a page that we've heard
   about before we flush that page to disk.

   This method informs bufferManager that an update has been applied.
   It is called by operations.c every time doUpdate, redoUpdate, or
   undoUpdate is called.

   @todo as implemented, loadPage() ... doOperation is not atomic!

*/
void removePendingEvent(int pageid) {
  
  Page * p;

  p = loadPage(pageid);

  pthread_mutex_lock(&(add_pending_mutex));
  p->pending--;
  
  assert(p->id == pageid);
  assert(p->pending >= 0);

  if(p->waiting && !p->pending) {
    assert(p->waiting == 1);
    pthread_cond_signal(&(p->noMorePending));
  }

  pthread_mutex_unlock(&(add_pending_mutex));

  unlock(p->loadlatch);


}