Fossil

**
** Procedures store and retrieve records from the repository
*/
#include "config.h"
#include "content.h"
#include <assert.h>










/*
** The artifact retrival cache
*/


static struct {
  i64 szTotal;         /* Total size of all entries in the cache */
  int n;               /* Current number of eache entries */
  int nAlloc;          /* Number of slots allocated in a[] */
  int nextAge;         /* Age counter for implementing LRU */
  int skipCnt;         /* Used to limit entries expelled from cache */
  struct cacheLine {   /* One instance of this for each cache entry */
    int rid;                  /* Artifact id */
    int age;                  /* Age.  Newer is larger */
    Blob content;             /* Content of the artifact */
  } *a;                /* The positive cache */
  Bag inCache;         /* Set of artifacts currently in cache */

  /*
  ** The missing artifact cache.
  **
  ** Artifacts whose record ID are in missingCache cannot be retrieved
  ** either because they are phantoms or because they are a delta that
  ** depends on a phantom.  Artifacts whose content we are certain is
  ** available are in availableCache.  If an artifact is in neither cache
  ** then its current availablity is unknown.
  */
  Bag missing;         /* Cache of artifacts that are incomplete */
  Bag available;       /* Cache of artifacts that are complete */
} contentCache;

/*
** Remove the oldest element from the content cache
*/
static void content_cache_expire_oldest(void){
  int i;
  int mnAge = contentCache.nextAge;
  int mn = -1;
  for(i=0; i<contentCache.n; i++){
    if( contentCache.a[i].age<mnAge ){
      mnAge = contentCache.a[i].age;
      mn = i;
    }
  }
  if( mn>=0 ){
    bag_remove(&contentCache.inCache, contentCache.a[mn].rid);
    contentCache.szTotal -= blob_size(&contentCache.a[mn].content);
    blob_reset(&contentCache.a[mn].content);
    contentCache.n--;
    contentCache.a[mn] = contentCache.a[contentCache.n];
  }
}

/*
** Add an entry to the content cache
*/
void content_cache_insert(int rid, Blob *pBlob){
  struct cacheLine *p;
  if( contentCache.n>500 || contentCache.szTotal>50000000 ){
    content_cache_expire_oldest();
  }
  if( contentCache.n>=contentCache.nAlloc ){
    contentCache.nAlloc = contentCache.nAlloc*2 + 10;
    contentCache.a = realloc(contentCache.a,
                             contentCache.nAlloc*sizeof(contentCache.a[0]));
    if( contentCache.a==0 ) fossil_panic("out of memory");
  }
  p = &contentCache.a[contentCache.n++];
  p->rid = rid;
  p->age = contentCache.nextAge++;
  contentCache.szTotal += blob_size(pBlob);
  p->content = *pBlob;
  blob_zero(pBlob);
  bag_insert(&contentCache.inCache, rid);
}

/*
** Clear the content cache.
*/
void content_clear_cache(void){
  int i;
  for(i=0; i<contentCache.n; i++){
    blob_reset(&contentCache.a[i].content);
  }
  bag_clear(&contentCache.missing);
  bag_clear(&contentCache.available);
  bag_clear(&contentCache.inCache);
  contentCache.n = 0;
  contentCache.szTotal = 0;
}

/*
** Return the srcid associated with rid.  Or return 0 if rid is 
** original content and not a delta.
*/
static int findSrcid(int rid){

/*
** Check to see if content is available for artifact "rid".  Return
** true if it is.  Return false if rid is a phantom or depends on
** a phantom.
*/
int content_is_available(int rid){
  int srcid;
  int depth = 0;  /* Limit to recursion depth */
  while( depth++ < 10000000 ){  
    if( bag_find(&contentCache.missing, rid) ){
      return 0;
    }
    if( bag_find(&contentCache.available, rid) ){
      return 1;
    }
    if( db_int(-1, "SELECT size FROM blob WHERE rid=%d", rid)<0 ){
      bag_insert(&contentCache.missing, rid);
      return 0;
    }
    srcid = findSrcid(rid);
    if( srcid==0 ){
      bag_insert(&contentCache.available, rid);
      return 1;
    }
    rid = srcid;



  }
  fossil_panic("delta-loop in repository");
  return 0;

}

/*
** Mark artifact rid as being available now.  Update the cache to
** show that everything that was formerly unavailable because rid
** was missing is now available.
*/

    blob_uncompress(pBlob, pBlob);
    rc = 1;
  }
  db_reset(&q);
  return rc;
}


/*
** Extract the content for ID rid and put it into the
** uninitialized blob.  Return 1 on success.  If the record
** is a phantom, zero pBlob and return 0.
*/
int content_get(int rid, Blob *pBlob){


  int rc;
  int i;
  int nextRid;

  assert( g.repositoryOpen );
  blob_zero(pBlob);
  if( rid==0 ) return 0;

  /* Early out if we know the content is not available */
  if( bag_find(&contentCache.missing, rid) ){


    return 0;
  }

  /* Look for the artifact in the cache first */
  if( bag_find(&contentCache.inCache, rid) ){
    for(i=0; i<contentCache.n; i++){
      if( contentCache.a[i].rid==rid ){

        blob_copy(pBlob, &contentCache.a[i].content);
        contentCache.a[i].age = contentCache.nextAge++;





        return 1;
      }
    }
  }

  nextRid = findSrcid(rid);
  if( nextRid==0 ){
    rc = content_of_blob(rid, pBlob);
  }else{
    int n = 1;
    int nAlloc = 10;
    int *a = 0;
    int mx;
    Blob delta, next;

    a = malloc( sizeof(a[0])*nAlloc );
    if( a==0 ) fossil_panic("out of memory");
    a[0] = rid;
    a[1] = nextRid;
    n = 1;
    while( !bag_find(&contentCache.inCache, nextRid)




        && (nextRid = findSrcid(nextRid))>0 ){
      n++;
      if( n>=nAlloc ){
        nAlloc = nAlloc*2 + 10;

        a = realloc(a, nAlloc*sizeof(a[0]));
        if( a==0 ) fossil_panic("out of memory");
      }

      a[n] = nextRid;
    }
    mx = n;
    rc = content_get(a[n], pBlob);

    n--;
    while( rc && n>=0 ){
      rc = content_of_blob(a[n], &delta);

      if( rc ){
        blob_delta_apply(pBlob, &delta, &next);
        blob_reset(&delta);


        if( (mx-n)%8==0 ){


          content_cache_insert(a[n+1], pBlob);


        }else{











          blob_reset(pBlob);
        }







        *pBlob = next;
      }
      n--;
    }

    free(a);

    if( !rc ) blob_reset(pBlob);


  }
  if( rc==0 ){
    bag_insert(&contentCache.missing, rid);
  }else{
    bag_insert(&contentCache.available, rid);
  }
  return rc;

  blob_write_to_file(&content, zFile);
}

/*
** When a record is converted from a phantom to a real record,
** if that record has other records that are derived by delta,
** then call manifest_crosslink() on those other records.
**
** Tail recursion is used to minimize stack depth.
*/
void after_dephantomize(int rid, int linkFlag){
  Stmt q;
  int nChildAlloc = 0;
  int *aChild = 0;

  while( rid ){
    int nChildUsed = 0;



    int i;

    if( linkFlag ){
      Blob content;
      content_get(rid, &content);
      manifest_crosslink(rid, &content);
      blob_reset(&content);
    }
    db_prepare(&q, "SELECT rid FROM delta WHERE srcid=%d", rid);
    while( db_step(&q)==SQLITE_ROW ){
      int child = db_column_int(&q, 0);
      if( nChildUsed>=nChildAlloc ){
        nChildAlloc = nChildAlloc*2 + 10;
        aChild = realloc(aChild, nChildAlloc*sizeof(aChild));
        if( aChild==0 ) fossil_panic("out of memory");
      }
      aChild[nChildUsed++] = child;
    }
    db_finalize(&q);
    for(i=1; i<nChildUsed; i++){
      after_dephantomize(aChild[i], 1);
    }
    rid = nChildUsed>0 ? aChild[0] : 0;
    linkFlag = 1;




  }
  free(aChild);
}

/*
** Write content into the database.  Return the record ID.  If the
** content is already in the database, just return the record ID.
**
** If srcId is specified, then pBlob is delta content from

static void rebuild_step(int rid, int size, Blob *pBase){
  static Stmt q1;
  Bag children;
  Blob copy;
  Blob *pUse;
  int nChild, i, cid;

  while( rid>0 ){

    /* Fix up the "blob.size" field if needed. */
    if( size!=blob_size(pBase) ){
      db_multi_exec(
         "UPDATE blob SET size=%d WHERE rid=%d", blob_size(pBase), rid
      );
    }
  
    /* Find all children of artifact rid */
    db_static_prepare(&q1, "SELECT rid FROM delta WHERE srcid=:rid");
    db_bind_int(&q1, ":rid", rid);
    bag_init(&children);
    while( db_step(&q1)==SQLITE_ROW ){
      int cid = db_column_int(&q1, 0);
      if( !bag_find(&bagDone, cid) ){
        bag_insert(&children, cid);
      }
    }
    nChild = bag_count(&children);
    db_reset(&q1);
  
    /* Crosslink the artifact */
    if( nChild==0 ){
      pUse = pBase;
    }else{
      blob_copy(&copy, pBase);
      pUse = ©
    }
    if( zFNameFormat==0 ){
      /* We are doing "fossil rebuild" */
      manifest_crosslink(rid, pUse);
    }else{
      /* We are doing "fossil deconstruct" */
      char *zUuid = db_text(0, "SELECT uuid FROM blob WHERE rid=%d", rid);
      char *zFile = mprintf(zFNameFormat, zUuid, zUuid+prefixLength);
      blob_write_to_file(pUse,zFile);
      free(zFile);
      free(zUuid);
    }
    blob_reset(pUse);
    rebuild_step_done(rid);
  
    /* Call all children recursively */
    rid = 0;
    for(cid=bag_first(&children), i=1; cid; cid=bag_next(&children, cid), i++){
      Stmt q2;
      int sz;






      db_prepare(&q2, "SELECT content, size FROM blob WHERE rid=%d", cid);
      if( db_step(&q2)==SQLITE_ROW && (sz = db_column_int(&q2,1))>=0 ){
        Blob delta, next;
        db_ephemeral_blob(&q2, 0, &delta);
        blob_uncompress(&delta, &delta);
        blob_delta_apply(pBase, &delta, &next);
        blob_reset(&delta);
        db_finalize(&q2);
        if( i<nChild ){
          rebuild_step(cid, sz, &next);
        }else{
          /* Tail recursion */
          rid = cid;
          size = sz;
          blob_reset(pBase);
          *pBase = next;
        }
      }else{
        db_finalize(&q2);
        blob_reset(pBase);
      }
    }
    bag_clear(&children);
  }
}

/*
** Check to see if the "sym-trunk" tag exists.  If not, create it
** and attach it to the very first check-in.
*/
static void rebuild_tag_trunk(void){

  blob_zero(&hash);
  blob_extract(pXfer->pIn, n, &content);
  if( uuid_is_shunned(blob_str(&pXfer->aToken[1])) ){
    /* Ignore files that have been shunned */
    return;
  }
  if( pXfer->nToken==4 ){
    Blob src, next;
    srcid = rid_from_uuid(&pXfer->aToken[2], 1);
    if( content_get(srcid, &src)==0 ){
      rid = content_put(&content, blob_str(&pXfer->aToken[1]), srcid);
      pXfer->nDanglingFile++;
      db_multi_exec("DELETE FROM phantom WHERE rid=%d", rid);
      content_make_public(rid);
      return;
    }
    pXfer->nDeltaRcvd++;
    blob_delta_apply(&src, &content, &next);
    blob_reset(&src);
    blob_reset(&content);
    content = next;
  }else{
    pXfer->nFileRcvd++;
  }
  sha1sum_blob(&content, &hash);
  if( !blob_eq_str(&pXfer->aToken[1], blob_str(&hash), -1) ){
    blob_appendf(&pXfer->err, "content does not match sha1 hash");
  }