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

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/**

  @file

  Generic page interface.  This file handles updates to the LSN, but
  leaves finer grained concurrency to the implementor of each of the
  page types.  This interface's primary purpose is to wrap common
  functionality together, and to delegate responsibility for page
  handling to other modules.
  
 Latching summary:

   Each page has an associated read/write lock.  This lock only
   protects the internal layout of the page, and the members of the
   page struct.  Here is how it is held in various circumstances:

   Record allocation:  Write lock
   Record read:        Read lock
   Read LSN            Read lock
   Record write       *READ LOCK*
   Write LSN           Write lock
 
 Any circumstance where these locks are held during an I/O operation
 is a bug.
 
*/


/* _XOPEN_SOURCE is needed for posix_memalign */
#define _XOPEN_SOURCE 600
#include <stdlib.h>

#include <config.h>
#include <lladd/common.h>
#include "latches.h"
#include "page.h"

#include <assert.h>
#include <stdio.h>

#include <lladd/constants.h>
#include <assert.h>
#include "blobManager.h"
#include "pageFile.h"

#include "page/slotted.h"
#include "page/fixed.h"

/* TODO:  Combine with buffer size... */
static int nextPage = 0;

static int lastAllocedPage;
static pthread_mutex_t lastAllocedPage_mutex;



/* ------ */

static pthread_mutex_t pageMallocMutex;
/** We need one dummy page for locking purposes, so this array has one extra page in it. */
Page pool[MAX_BUFFER_SIZE+1];

void pageWriteLSN(Page * page, lsn_t lsn) {
  /* unlocked since we're only called by a function that holds the writelock. */
  /*  *(long *)(page->memAddr + START_OF_LSN) = page->LSN; */
  if(page->LSN < lsn) {
    page->LSN = lsn;
    *lsn_ptr(page) = page->LSN;
  } 
}

lsn_t pageReadLSN(const Page * page) {
  lsn_t ret;

  readlock(page->rwlatch, 259); 
  /*  ret = *(long *)(page->memAddr + START_OF_LSN); */
  ret = *lsn_ptr(page);
  readunlock(page->rwlatch); 

  return ret;
}



static void pageReallocNoLock(Page *p, int id) {
  p->id = id;
  p->LSN = 0;
  p->dirty = 0;
}

/* ----- end static functions ----- */

/* ----- (de)initialization functions.  Do not need to support multithreading. -----*/

/**
 * pageInit() initializes all the important variables needed in
 * all the functions dealing with pages.
 */
void pageInit() {

  nextPage = 0;
	
  pthread_mutex_init(&pageMallocMutex, NULL);

  for(int i = 0; i < MAX_BUFFER_SIZE+1; i++) {
    pool[i].rwlatch = initlock();
    pool[i].loadlatch = initlock();
    int ret = posix_memalign((void*)(&(pool[i].memAddr)), PAGE_SIZE, PAGE_SIZE);

    assert(!ret);
  }
  pthread_mutex_init(&lastAllocedPage_mutex , NULL);
	
  lastAllocedPage = 0; 
  slottedPageInit();

}

void pageDeInit() {
  for(int i = 0; i < MAX_BUFFER_SIZE+1; i++) {
    deletelock(pool[i].rwlatch);
    deletelock(pool[i].loadlatch);
    free(pool[i].memAddr); // breaks efence
  }
  pthread_mutex_destroy(&lastAllocedPage_mutex);
}

void pageCommit(int xid) {
}

void pageAbort(int xid) {
}
/*
static int pageAllocUnlocked() {
  int ret = lastAllocedPage;
  Page * p;

  lastAllocedPage += 1;
  
  p = loadPage(lastAllocedPage);
  / ** TODO Incorrect, but this kludge tricks the tests (for now) * /
  while(*page_type_ptr(p) != UNINITIALIZED_PAGE) {
    releasePage(p);
    lastAllocedPage++;
    p = loadPage(lastAllocedPage);
  }
  releasePage(p);

  return ret;
}*/

/**
   @todo DATA CORRUPTION BUG pageAllocMultiple needs to scan forward in the store file until
   it finds page(s) with type = UNINITIALIZED_PAGE.  Otherwise, after recovery, it will trash the storefile.

   A better way to implement this is probably to reserve the first
   slot of the first page in the storefile for metadata, and to keep
   lastFreepage there, instead of in RAM.
*/
/*int pageAlloc() {
  pthread_mutex_lock(&lastAllocedPage_mutex);  
  int ret = pageAllocUnlocked();
  pthread_mutex_unlock(&lastAllocedPage_mutex);
  return ret;
  }*/




/** @todo Does pageRealloc really need to obtain a lock? */
void pageRealloc(Page *p, int id) {
  writelock(p->rwlatch, 10);
  pageReallocNoLock(p,id);
  writeunlock(p->rwlatch);
}


/** 
	Allocate a new page. 
	@return A pointer to the new page.  This memory is part of a pool, 
	        and should never be freed manually.  Instead, you can 
		reclaim it with pageRealloc()
 */
Page *pageMalloc() {
  Page *page;

  pthread_mutex_lock(&pageMallocMutex);
  
  page = &(pool[nextPage]);
  
  nextPage++;
  /* There's a dummy page that we need to keep around, thus the +1 */
  assert(nextPage <= MAX_BUFFER_SIZE + 1); 

  pthread_mutex_unlock(&pageMallocMutex);

  return page;
}

/*void setRecordType(Page * page, recordid rid, int slot_type) {
  if(*page_type_ptr(page) == SLOTTED_PAGE) {
    slottedSetType(page, rid.slot, slot_type);
  }
  }*/


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

  assert( (p->id == rid.page) && (p->memAddr != NULL) );	
  
  if(rid.size > BLOB_THRESHOLD_SIZE) {
    writeBlob(xid, p, lsn, rid, dat);
  } else if(*page_type_ptr(p) == SLOTTED_PAGE) {
    slottedWrite(xid, p, lsn, rid, dat);
  } else if(*page_type_ptr(p) == FIXED_PAGE  || *page_type_ptr(p)==ARRAY_LIST_PAGE || !*page_type_ptr(p) )  {
    fixedWrite(p, rid, dat);
  } else {
    abort();
  }
  assert( (p->id == rid.page) && (p->memAddr != NULL) );	
  
  writelock(p->rwlatch, 225);  /* Need a writelock so that we can update the lsn. */
  pageWriteLSN(p, lsn);
  unlock(p->rwlatch);    

}

void readRecord(int xid, Page * p, recordid rid, void *buf) {
  assert(rid.page == p->id); 
  
  int page_type = *page_type_ptr(p);

  if(rid.size > BLOB_THRESHOLD_SIZE) {
    readBlob(xid, p, rid, buf);
  } else if(page_type == SLOTTED_PAGE) {
    slottedRead(xid, p, rid, buf);
    /* FIXED_PAGES can function correctly even if they have not been
       initialized. */
  } else if(page_type == FIXED_PAGE || page_type==ARRAY_LIST_PAGE || !page_type) { 
    fixedRead(p, rid, buf);
  } else {
    abort();
  }
  assert(rid.page == p->id); 
}


void readRecordUnlocked(int xid, Page * p, recordid rid, void *buf) {
  assert(rid.page == p->id); 
  
  int page_type = *page_type_ptr(p);

  if(rid.size > BLOB_THRESHOLD_SIZE) {
    abort(); /* Unsupported for now. */
    readBlob(xid, p, rid, buf);
  } else if(page_type == SLOTTED_PAGE) {
    slottedReadUnlocked(xid, p, rid, buf);
    /* FIXED_PAGES can function correctly even if they have not been
       initialized. */
  } else if(page_type == FIXED_PAGE || !page_type) { 
    fixedReadUnlocked(p, rid, buf);
  } else {
    abort();
  }
  assert(rid.page == p->id); 
}
/** @todo getRecordType is a hack.  Instead, each record type should
    implement code that decides whether a record exists, and returns its size
    or -1.  Then, getRecordType coudl call that function directly depending on 
	  page type, etc.

	  A complementary function getRecordSize could return the size value.

*/
int getRecordTypeUnlocked(int xid, Page * p, recordid rid) {
  assert(rid.page == p->id);
  
  int page_type = *page_type_ptr(p);
  if(page_type == UNINITIALIZED_PAGE) {
    return UNINITIALIZED_RECORD;	
    
  } else if(page_type == SLOTTED_PAGE) {
    if(*numslots_ptr(p) <= rid.slot || *slot_length_ptr(p, rid.slot) == INVALID_SLOT) {
      return UNINITIALIZED_PAGE;
    } else if(*slot_length_ptr(p, rid.slot) == BLOB_REC_SIZE) {
      return BLOB_RECORD; 
    } else {
      return SLOTTED_RECORD;
    }
  } else if(page_type == FIXED_PAGE || page_type == ARRAY_LIST_PAGE) {
    return  (fixedPageCount(p) > rid.slot) ? 
      FIXED_RECORD : UNINITIALIZED_RECORD;
  } else {
    abort();
    return UNINITIALIZED_RECORD;
  }
}

int getRecordType(int xid, Page * p, recordid rid) {
	readlock(p->rwlatch, 343);
	int ret = getRecordTypeUnlocked(xid, p, rid);
	unlock(p->rwlatch);
	return ret;
}
/** @todo implemenet getRecordLength for blobs and fixed length pages. */
int getRecordSize(int xid, Page * p, recordid rid) {
  readlock(p->rwlatch, 353);
  int ret = getRecordTypeUnlocked(xid, p, rid);
  if(ret == UNINITIALIZED_RECORD) {
    ret = -1;
  } else if(ret == SLOTTED_RECORD) {
    ret = *slot_length_ptr(p, rid.slot);
  } else { 
    abort(); // unimplemented for fixed length pages and blobs.
  }
  unlock(p->rwlatch);
  return ret;
}

void writeRecordUnlocked(int xid, Page * p, lsn_t lsn, recordid rid, const void *dat) {

  assert( (p->id == rid.page) && (p->memAddr != NULL) );	
  
  if(rid.size > BLOB_THRESHOLD_SIZE) {
    abort();
    writeBlob(xid, p, lsn, rid, dat);
  } else if(*page_type_ptr(p) == SLOTTED_PAGE) {
    slottedWriteUnlocked(xid, p, lsn, rid, dat);
  } else if(*page_type_ptr(p) == FIXED_PAGE  || *page_type_ptr(p)==ARRAY_LIST_PAGE || !*page_type_ptr(p) )  {
    fixedWriteUnlocked(p, rid, dat);
  } else {
    abort();
  }
  assert( (p->id == rid.page) && (p->memAddr != NULL) );	
  
  writelock(p->rwlatch, 225);  /* Need a writelock so that we can update the lsn. */
  pageWriteLSN(p, lsn);
  unlock(p->rwlatch);    

}