database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-08-05 15:55:57 +03:00
Code Activity

Enhanced comments in wal.c and declare some procedure parameters "const".

Browse Source 
No changes to the generated code.

FossilOrigin-Name: d0e4375b8a784d4e4ae66caababac919edd61883
This commit is contained in:
drh
2010-12-15 21:02:06 +00:00
parent 901e994b8b
commit d9c9b78e6c
3 changed files with 51 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

47
src/wal.c
View File

@@ -458,14 +458,14 @@ typedef u16 ht_slot;
*/
struct WalIterator {
int iPrior; /* Last result returned from the iterator */
int nSegment; /* Size of the aSegment[] array */
int nSegment; /* Number of entries in aSegment[] */
struct WalSegment {
int iNext; /* Next slot in aIndex[] not yet returned */
ht_slot *aIndex; /* i0, i1, i2... such that aPgno[iN] ascend */
u32 *aPgno; /* Array of page numbers. */
int nEntry; /* Max size of aPgno[] and aIndex[] arrays */
int nEntry; /* Nr. of entries in aPgno[] and aIndex[] */
int iZero; /* Frame number associated with aPgno[0] */
} aSegment[1]; /* One for every 32KB page in the WAL */
} aSegment[1]; /* One for every 32KB page in the wal-index */
};
/*
@@ -1329,9 +1329,29 @@ static int walIteratorNext(
/*
** This function merges two sorted lists into a single sorted list.
**
** aLeft[] and aRight[] are arrays of indices. The sort key is
** aContent[aLeft[]] and aContent[aRight[]]. Upon entry, the following
** is guaranteed for all J<K:
**
** aContent[aLeft[J]] < aContent[aLeft[K]]
** aContent[aRight[J]] < aContent[aRight[K]]
**
** This routine overwrites aRight[] with a new (probably longer) sequence
** of indices such that the aRight[] contains every index that appears in
** either aLeft[] or the old aRight[] and such that the second condition
** above is still met.
**
** The aContent[aLeft[X]] values will be unique for all X. And the
** aContent[aRight[X]] values will be unique too. But there might be
** one or more combinations of X and Y such that
**
** aLeft[X]!=aRight[Y] && aContent[aLeft[X]] == aContent[aRight[Y]]
**
** When that happens, omit the aLeft[X] and use the aRight[Y] index.
*/
static void walMerge(
u32 *aContent, /* Pages in wal */
const u32 *aContent, /* Pages in wal - keys for the sort */
ht_slot *aLeft, /* IN: Left hand input list */
int nLeft, /* IN: Elements in array *paLeft */
ht_slot **paRight, /* IN/OUT: Right hand input list */
@@ -1371,10 +1391,24 @@ static void walMerge(
}
/*
** Sort the elements in list aList, removing any duplicates.
** Sort the elements in list aList using aContent[] as the sort key.
** Remove elements with duplicate keys, preferring to keep the
** larger aList[] values.
**
** The aList[] entries are indices into aContent[]. The values in
** aList[] are to be sorted so that for all J<K:
**
** aContent[aList[J]] < aContent[aList[K]]
**
** For any X and Y such that
**
** aContent[aList[X]] == aContent[aList[Y]]
**
** Keep the larger of the two values aList[X] and aList[Y] and discard
** the smaller.
*/
static void walMergesort(
u32 *aContent, /* Pages in wal */
const u32 *aContent, /* Pages in wal */
ht_slot *aBuffer, /* Buffer of at least *pnList items to use */
ht_slot *aList, /* IN/OUT: List to sort */
int *pnList /* IN/OUT: Number of elements in aList[] */
@@ -1439,6 +1473,7 @@ static void walIteratorFree(WalIterator *p){
/*
** Construct a WalInterator object that can be used to loop over all
** pages in the WAL in ascending order. The caller must hold the checkpoint
** lock.
**
** On success, make *pp point to the newly allocated WalInterator object
** return SQLITE_OK. Otherwise, return an error code. If this routine