stasis-aries-wal/src/stasis/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 <stasis/common.h>
#include <stasis/latches.h>
#include <stasis/page.h>

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

#include <stasis/constants.h>
#include <assert.h>
#include <stasis/blobManager.h>
#include <stasis/lockManager.h>
#include <stasis/compensations.h>
#include <stasis/page/slotted.h>
#include <stasis/page/fixed.h>
#include <stasis/page/indirect.h>
#include <stasis/operations/arrayList.h>
#include <stasis/bufferPool.h>
#include <stasis/truncation.h>

static page_impl page_impls[MAX_PAGE_TYPE];

void stasis_page_lsn_write(int xid, Page * page, lsn_t lsn) {
  assertlocked(page->rwlatch);

  if(page->LSN < lsn) {
    page->LSN = lsn;
  }
  dirtyPages_add(page);
  return;
}

lsn_t stasis_page_lsn_read(const Page * page) {
  assertlocked(page->rwlatch);
  return page->LSN;
}

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

/**
 * initializes all the important variables needed in
 * all the functions dealing with pages.
 */
void stasis_page_init() {
  slottedPageInit();
  fixedPageInit();

  stasis_page_impl_register(slottedImpl());
  stasis_page_impl_register(fixedImpl());
  stasis_page_impl_register(boundaryTagImpl());
  stasis_page_impl_register(arrayListImpl());
  stasis_page_impl_register(blobImpl());
  stasis_page_impl_register(indirectImpl());
  stasis_page_impl_register(lsmRootImpl());
  stasis_page_impl_register(slottedLsnFreeImpl());
}

void stasis_page_deinit() {

  for(int i = 0; i < MAX_PAGE_TYPE; i++) {
    page_impl p = { 0 };
    page_impls[i] = p;
  }

  fixedPageDeinit();
  slottedPageDeinit();
}

int stasis_page_impl_register(page_impl p) {
  assert(page_impls[p.page_type].page_type == 0);
  page_impls[p.page_type] = p;
  return 0;
}
void stasis_record_write(int xid, Page * p, lsn_t lsn, recordid rid, const byte *dat) {
  assertlocked(p->rwlatch);
  assert( (p->id == rid.page) && (p->memAddr != NULL) );
  assert(rid.size <= BLOB_THRESHOLD_SIZE);

  byte * buf = stasis_record_write_begin(xid, p, rid);
  memcpy(buf, dat, stasis_record_length_read(xid, p, rid));
  stasis_record_write_done(xid,p,rid,buf);
  assert( (p->id == rid.page) && (p->memAddr != NULL) );
}
int stasis_record_read(int xid, Page * p, recordid rid, byte *buf) {
  assertlocked(p->rwlatch);
  assert(rid.page == p->id);
  assert(rid.size <= BLOB_THRESHOLD_SIZE);

  const byte * dat = stasis_record_read_begin(xid,p,rid);
  memcpy(buf, dat, stasis_record_length_read(xid,p,rid));

  return 0;

}
/**
   @todo stasis_record_dereference should dispatch via page_impl...
 */
recordid stasis_record_dereference(int xid, Page * p, recordid rid) {
  assertlocked(p->rwlatch);

  int page_type = *stasis_page_type_ptr(p);
  if(page_type == INDIRECT_PAGE) {
    rid = dereferenceIndirectRID(xid, rid);
  } else if(page_type == ARRAY_LIST_PAGE) {
    rid = dereferenceArrayListRid(xid, p, rid.slot);
  }
  return rid;
}

/// --------------  Dispatch functions

const byte * stasis_record_read_begin(int xid, Page * p, recordid rid) {
  assertlocked(p->rwlatch);

  int page_type = *stasis_page_type_ptr(p);
  assert(page_type);
  return page_impls[page_type].recordRead(xid, p, rid);
}
byte * stasis_record_write_begin(int xid, Page * p, recordid rid) {
  assertlocked(p->rwlatch);

  int page_type = *stasis_page_type_ptr(p);
  assert(page_type);
  assert(stasis_record_length_read(xid, p, rid) ==  stasis_record_type_to_size(rid.size));
  return page_impls[page_type].recordWrite(xid, p, rid);
}
void stasis_record_read_done(int xid, Page *p, recordid rid, const byte *b) {
  int page_type = *stasis_page_type_ptr(p);
  if(page_impls[page_type].recordReadDone) {
    page_impls[page_type].recordReadDone(xid,p,rid,b);
  }
}
void stasis_record_write_done(int xid, Page *p, recordid rid, byte *b) {
  int page_type = *stasis_page_type_ptr(p);
  if(page_impls[page_type].recordWriteDone) {
    page_impls[page_type].recordWriteDone(xid,p,rid,b);
  }
}
int stasis_record_type_read(int xid, Page *p, recordid rid) {
  assertlocked(p->rwlatch);
  if(page_impls[*stasis_page_type_ptr(p)].recordGetType) 
    return page_impls[*stasis_page_type_ptr(p)].recordGetType(xid, p, rid);
  else
    return INVALID_SLOT;
}
void stasis_record_type_write(int xid, Page *p, recordid rid, int type) {
  assertlocked(p->rwlatch);
  page_impls[*stasis_page_type_ptr(p)]
    .recordSetType(xid, p, rid, type);
}
int stasis_record_length_read(int xid, Page *p, recordid rid) {
  assertlocked(p->rwlatch);
  return page_impls[*stasis_page_type_ptr(p)]
    .recordGetLength(xid,p,rid);
}
recordid stasis_record_first(int xid, Page * p){
  return page_impls[*stasis_page_type_ptr(p)]
    .recordFirst(xid,p);
}
recordid stasis_record_next(int xid, Page * p, recordid prev){
  return page_impls[*stasis_page_type_ptr(p)]
    .recordNext(xid,p,prev);
}
recordid stasis_record_alloc_begin(int xid, Page * p, int size){
  return page_impls[*stasis_page_type_ptr(p)]
    .recordPreAlloc(xid,p,size);
}
void stasis_record_alloc_done(int xid, Page * p, recordid rid){
  page_impls[*stasis_page_type_ptr(p)]
    .recordPostAlloc(xid, p, rid);
}
void stasis_record_free(int xid, Page * p, recordid rid){
  page_impls[*stasis_page_type_ptr(p)]
    .recordFree(xid, p, rid);
}
int stasis_block_supported(int xid, Page * p){
  return page_impls[*stasis_page_type_ptr(p)]
    .isBlockSupported(xid, p);
}
block_t * stasis_block_first(int xid, Page * p){
  int t = *stasis_page_type_ptr(p);
  return page_impls[t]
    .blockFirst(xid, p);
}
block_t * stasis_block_next(int xid, Page * p, block_t * prev){
  return page_impls[*stasis_page_type_ptr(p)]
    .blockNext(xid, p,prev);
}
void stasis_block_done(int xid, Page * p, block_t * done){
  page_impls[*stasis_page_type_ptr(p)]
    .blockDone(xid, p,done);
}
int stasis_record_freespace(int xid, Page * p){
  return page_impls[*stasis_page_type_ptr(p)]
    .pageFreespace(xid, p);
}
void stasis_record_compact(Page * p){
  page_impls[*stasis_page_type_ptr(p)]
    .pageCompact(p);
}
/** @todo How should the LSN of pages without a page_type be handled?

    This only works because we don't have LSN-free pages yet.  With
    LSN-free pages, we'll need special "loadPageForAlloc(), and
    loadPageOfType() methods (or something...)
*/
void stasis_page_loaded(Page * p){
  short type = *stasis_page_type_ptr(p);
  if(type) {
    assert(page_impls[type].page_type == type);
    page_impls[type].pageLoaded(p);
  } else {
    p->LSN = *stasis_page_lsn_ptr(p);  // XXX kludge - shouldn't special-case UNINITIALIZED_PAGE
  }
}
void stasis_page_flushed(Page * p){
  short type = *stasis_page_type_ptr(p);
  if(type) {
    assert(page_impls[type].page_type == type);
    page_impls[type].pageFlushed(p);
  } else {
    *stasis_page_lsn_ptr(p) = p->LSN;
  }
}
void stasis_page_cleanup(Page * p) { 
  short type = *stasis_page_type_ptr(p);
  if(type) { 
    assert(page_impls[type].page_type == type);
    page_impls[type].pageCleanup(p);
  } 
}

/// Generic block implementations

static int blkTrue(block_t *b) { return 1; }
static int blkFalse(block_t *b) { return 0; }

typedef struct genericBlockImpl {
  Page * p;
  recordid pos;
} genericBlockImpl;

/**
   @todo The block API should pass around xids.
 */
static const byte * blkFirst(block_t * b) {
  genericBlockImpl * impl = b->impl;
  impl->pos = stasis_record_first(-1, impl->p);
  if(! memcmp(&(impl->pos), &(NULLRID), sizeof(recordid))) {
    return 0;
  } else {
    return stasis_record_read_begin(-1, impl->p, impl->pos);
  }
}
static const byte * blkNext(block_t * b) {
  genericBlockImpl * impl = b->impl;
  impl->pos = stasis_record_next(-1, impl->p, impl->pos);
  if(! memcmp(&(impl->pos), &NULLRID, sizeof(recordid))) {
    return 0;
  } else {
    return stasis_record_read_begin(-1, impl->p, impl->pos);
  }
}
static int blkSize(block_t * b) {
  genericBlockImpl * impl = b->impl;
  return stasis_record_type_to_size(impl->pos.size);
}
static void blkRelease(block_t * b) {
  free(b->impl);
  free(b);
}

block_t genericBlock = {
  blkTrue, // isValid
  blkFalse, //isOneValue
  blkFalse, //isValueSorted
  blkFalse, //isPosContig
  blkFirst,
  blkNext,
  blkSize,
  0, //recordCount
  0, //ptrArray can't do pointer array efficiently...
  0, //sizePtrArray
  blkFalse, //recordFixedLen
  0, //packedArray
  blkRelease,
  0
};

block_t* stasis_block_first_default_impl(int xid, Page * p) {
  block_t* ret = malloc(sizeof(block_t));
  *ret = genericBlock;
  genericBlockImpl impl = { p, NULLRID };
  ret->impl = malloc(sizeof(genericBlockImpl));
  *(genericBlockImpl*)(ret->impl) = impl;
  return ret;
}
block_t* stasis_block_next_default_impl(int xid, Page *p, block_t *prev) {
  stasis_block_done_default_impl(xid, p, prev);
  return 0;  // definitely done.
}
void stasis_block_done_default_impl(int xid, Page *p, block_t *b) {
  free(b->impl);
  free(b);
}