#include "sds.h"
#include "ziplist.h"
+/* Important note: the ZIP_END value is used to depict the end of the
+ * ziplist structure. When a pointer contains an entry, the first couple
+ * of bytes contain the encoded length of the previous entry. This length
+ * is encoded as ZIP_ENC_RAW length, so the first two bits will contain 00
+ * and the byte will therefore never have a value of 255. */
#define ZIP_END 255
#define ZIP_BIGLEN 254
/* Utility macros */
#define ZIPLIST_BYTES(zl) (*((unsigned int*)(zl)))
-#define ZIPLIST_LENGTH(zl) (*((zl)+sizeof(unsigned int)))
-#define ZIPLIST_HEADER_SIZE (sizeof(unsigned int)+1)
+#define ZIPLIST_TAIL_OFFSET(zl) (*((zl)+sizeof(unsigned int)))
+#define ZIPLIST_LENGTH(zl) (*((zl)+2*sizeof(unsigned int)))
+#define ZIPLIST_HEADER_SIZE (2*sizeof(unsigned int)+1)
#define ZIPLIST_INCR_LENGTH(zl,incr) { \
if (ZIPLIST_LENGTH(zl) < ZIP_BIGLEN) ZIPLIST_LENGTH(zl)+=incr; }
+typedef struct zlentry {
+ unsigned int prevrawlensize, prevrawlen;
+ unsigned int lensize, len;
+ unsigned int headersize;
+ unsigned char encoding;
+ unsigned char *p;
+} zlentry;
+
/* Return bytes needed to store integer encoded by 'encoding' */
static unsigned int zipEncodingSize(char encoding) {
if (encoding == ZIP_ENC_SHORT) {
return len;
}
+/* Return the difference in number of bytes needed to store the new length
+ * "len" on the entry pointed to by "p". */
+static int zipPrevLenByteDiff(unsigned char *p, unsigned int len) {
+ unsigned int prevlensize;
+ zipDecodeLength(p,&prevlensize);
+ return zipEncodeLength(NULL,ZIP_ENC_RAW,len)-prevlensize;
+}
+
/* Check if string pointed to by 'entry' can be encoded as an integer.
* Stores the integer value in 'v' and its encoding in 'encoding'.
* Warning: this function requires a NULL-terminated string! */
char *eptr;
if (entry[0] == '-' || (entry[0] >= '0' && entry[0] <= '9')) {
- value = strtoll(entry,&eptr,10);
+ value = strtoll((char*)entry,&eptr,10);
if (eptr[0] != '\0') return 0;
if (value >= SHRT_MIN && value <= SHRT_MAX) {
*encoding = ZIP_ENC_SHORT;
return ret;
}
-/* Return the total amount used by an entry (encoded length + payload). */
+/* Return a struct with all information about an entry. */
+static zlentry zipEntry(unsigned char *p) {
+ zlentry e;
+ e.prevrawlen = zipDecodeLength(p,&e.prevrawlensize);
+ e.len = zipDecodeLength(p+e.prevrawlensize,&e.lensize);
+ e.headersize = e.prevrawlensize+e.lensize;
+ e.encoding = ZIP_ENCODING(p+e.prevrawlensize);
+ e.p = p;
+ return e;
+}
+
+/* Return the total number of bytes used by the entry at "p". */
static unsigned int zipRawEntryLength(unsigned char *p) {
- unsigned int lensize, len;
- len = zipDecodeLength(p, &lensize);
- return lensize + len;
+ zlentry e = zipEntry(p);
+ return e.headersize + e.len;
}
/* Create a new empty ziplist. */
unsigned int bytes = ZIPLIST_HEADER_SIZE+1;
unsigned char *zl = zmalloc(bytes);
ZIPLIST_BYTES(zl) = bytes;
+ ZIPLIST_TAIL_OFFSET(zl) = ZIPLIST_HEADER_SIZE;
ZIPLIST_LENGTH(zl) = 0;
zl[bytes-1] = ZIP_END;
return zl;
p += zipRawEntryLength(p);
}
return q;
+
+/* Delete "num" entries, starting at "p". Returns pointer to the ziplist. */
+static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, int num) {
+ unsigned int i, totlen, deleted = 0;
+ int nextdiff = 0;
+ zlentry first = zipEntry(p);
+ for (i = 0; p[0] != ZIP_END && i < num; i++) {
+ p += zipRawEntryLength(p);
+ deleted++;
+ }
+
+ totlen = p-first.p;
+ if (totlen > 0) {
+ if (p[0] != ZIP_END) {
+ /* Tricky: storing the prevlen in this entry might reduce or
+ * increase the number of bytes needed, compared to the current
+ * prevlen. Note that we can always store this length because
+ * it was previously stored by an entry that is being deleted. */
+ nextdiff = zipPrevLenByteDiff(p,first.prevrawlen);
+ zipEncodeLength(p-nextdiff,ZIP_ENC_RAW,first.prevrawlen);
+
+ /* Update offset for tail */
+ ZIPLIST_TAIL_OFFSET(zl) -= totlen+nextdiff;
+
+ /* Move tail to the front of the ziplist */
+ memmove(first.p,p-nextdiff,ZIPLIST_BYTES(zl)-(p-zl)-1+nextdiff);
+ } else {
+ /* The entire tail was deleted. No need to move memory. */
+ ZIPLIST_TAIL_OFFSET(zl) = (first.p-zl)-first.prevrawlen;
+ }
+
+ /* Resize and update length */
+ zl = ziplistResize(zl, ZIPLIST_BYTES(zl)-totlen+nextdiff);
+ ZIPLIST_INCR_LENGTH(zl,-deleted);
+ }
+ return zl;
}
-unsigned char *ziplistPush(unsigned char *zl, unsigned char *entry, unsigned int elen, int where) {
- unsigned int curlen = ZIPLIST_BYTES(zl), reqlen;
- unsigned char *p;
+/* Insert item at "p". */
+static unsigned char *__ziplistInsert(unsigned char *zl, unsigned char *p, unsigned char *s, unsigned int slen) {
+ unsigned int curlen = ZIPLIST_BYTES(zl), reqlen, prevlen = 0;
+ unsigned int offset, nextdiff = 0;
+ unsigned char *tail;
char encoding = ZIP_ENC_RAW;
long long value;
+ zlentry entry;
+
+ /* Find out prevlen for the entry that is inserted. */
+ if (p[0] != ZIP_END) {
+ entry = zipEntry(p);
+ prevlen = entry.prevrawlen;
+ } else {
+ tail = ziplistTail(zl);
+ if (tail[0] != ZIP_END) {
+ prevlen = zipRawEntryLength(tail);
+ }
+ }
/* See if the entry can be encoded */
- if (zipTryEncoding(entry,&value,&encoding)) {
+ if (zipTryEncoding(s,&value,&encoding)) {
reqlen = zipEncodingSize(encoding);
} else {
- reqlen = elen;
+ reqlen = slen;
}
- reqlen += zipEncodeLength(NULL,encoding,elen);
-
- /* Resize the ziplist and move if needed */
- zl = ziplistResize(zl,curlen+reqlen);
- if (where == ZIPLIST_HEAD) {
- p = zl+ZIPLIST_HEADER_SIZE;
- if (*p != ZIP_END) {
- /* Subtract one because of the ZIP_END bytes */
- memmove(p+reqlen,p,curlen-ZIPLIST_HEADER_SIZE-1);
- }
+
+ /* We need space for both the length of the previous entry and
+ * the length of the payload. */
+ reqlen += zipEncodeLength(NULL,ZIP_ENC_RAW,prevlen);
+ reqlen += zipEncodeLength(NULL,encoding,slen);
+
+ /* When the insert position is not equal to the tail, we need to
+ * make sure that the next entry can hold this entry's length in
+ * its prevlen field. */
+ nextdiff = p[0] != ZIP_END ? zipPrevLenByteDiff(p,reqlen) : 0;
+
+ /* Store offset because a realloc may change the address of zl. */
+ offset = p-zl;
+ zl = ziplistResize(zl,curlen+reqlen+nextdiff);
+ p = zl+offset;
+
+ /* Apply memory move when necessary and update tail offset. */
+ if (p[0] != ZIP_END) {
+ /* Subtract one because of the ZIP_END bytes */
+ memmove(p+reqlen,p-nextdiff,curlen-offset-1+nextdiff);
+ /* Encode this entry's raw length in the next entry. */
+ zipEncodeLength(p+reqlen,ZIP_ENC_RAW,reqlen);
+ /* Update offset for tail */
+ ZIPLIST_TAIL_OFFSET(zl) += reqlen+nextdiff;
} else {
- p = zl+curlen-1;
+ /* This element will be the new tail. */
+ ZIPLIST_TAIL_OFFSET(zl) = p-zl;
}
/* Write the entry */
- p += zipEncodeLength(p,encoding,elen);
+ p += zipEncodeLength(p,ZIP_ENC_RAW,prevlen);
+ p += zipEncodeLength(p,encoding,slen);
if (encoding != ZIP_ENC_RAW) {
zipSaveInteger(p,value,encoding);
} else {
- memcpy(p,entry,elen);
+ memcpy(p,s,slen);
}
ZIPLIST_INCR_LENGTH(zl,1);
return zl;
}
+unsigned char *ziplistPush(unsigned char *zl, unsigned char *s, unsigned int slen, int where) {
+ unsigned char *p;
+ p = (where == ZIPLIST_HEAD) ? ziplistHead(zl) : (zl+ZIPLIST_BYTES(zl)-1);
+ return __ziplistInsert(zl,p,s,slen);
+}
+
unsigned char *ziplistPop(unsigned char *zl, sds *target, int where) {
- unsigned int curlen = ZIPLIST_BYTES(zl), rawlen;
- unsigned int len, lensize;
+ zlentry entry;
unsigned char *p;
long long value;
if (target) *target = NULL;
/* Get pointer to element to remove */
p = (where == ZIPLIST_HEAD) ? ziplistHead(zl) : ziplistTail(zl);
if (*p == ZIP_END) return zl;
- len = zipDecodeLength(p,&lensize);
+
+ entry = zipEntry(p);
if (target) {
- if (ZIP_ENCODING(p) == ZIP_ENC_RAW) {
- *target = sdsnewlen(p+lensize,len);
+ if (entry.encoding == ZIP_ENC_RAW) {
+ *target = sdsnewlen(p+entry.headersize,entry.len);
} else {
- value = zipLoadInteger(p+lensize,ZIP_ENCODING(p));
+ value = zipLoadInteger(p+entry.headersize,entry.encoding);
*target = sdscatprintf(sdsempty(), "%lld", value);
}
}
- /* Move list to front when popping from the head */
- rawlen = lensize+len;
- if (where == ZIPLIST_HEAD) {
- memmove(p,p+rawlen,curlen-ZIPLIST_HEADER_SIZE-len);
- }
-
- /* Resize and update length */
- zl = ziplistResize(zl,curlen-rawlen);
- ZIPLIST_INCR_LENGTH(zl,-1);
+ zl = __ziplistDelete(zl,p,1);
return zl;
}
* on the encoding of the entry. 'e' is always set to NULL to be able
* to find out whether the string pointer or the integer value was set.
* Return 0 if 'p' points to the end of the zipmap, 1 otherwise. */
-unsigned int ziplistGet(unsigned char *p, unsigned char **e, unsigned int *elen, long long *v) {
- unsigned int len, lensize;
+unsigned int ziplistGet(unsigned char *p, unsigned char **sstr, unsigned int *slen, long long *sval) {
+ zlentry entry;
if (*p == ZIP_END) return 0;
- if (e) *e = NULL;
- len = zipDecodeLength(p,&lensize);
- if (ZIP_ENCODING(p) == ZIP_ENC_RAW) {
- if (e) {
- *elen = len;
- *e = p+lensize;
+ if (sstr) *sstr = NULL;
+
+ entry = zipEntry(p);
+ if (entry.encoding == ZIP_ENC_RAW) {
+ if (sstr) {
+ *slen = entry.len;
+ *sstr = p+entry.headersize;
}
} else {
- if (v) {
- *v = zipLoadInteger(p+lensize,ZIP_ENCODING(p));
+ if (sval) {
+ *sval = zipLoadInteger(p+entry.headersize,entry.encoding);
}
}
return 1;
/* Delete a range of entries from the ziplist. */
unsigned char *ziplistDeleteRange(unsigned char *zl, unsigned int index, unsigned int num) {
- unsigned char *p, *first = ziplistIndex(zl, index);
- unsigned int i, deleted = 0, totlen, newlen;
- for (p = first, i = 0; *p != ZIP_END && i < num; i++) {
- p += zipRawEntryLength(p);
- deleted++;
- }
-
- totlen = p-first;
- if (totlen > 0) {
- /* Move current tail to the new tail when there *is* a tail */
- if (*p != ZIP_END) memmove(first,p,ZIPLIST_BYTES(zl)-(p-zl)-1);
-
- /* Resize and update length */
- zl = ziplistResize(zl, ZIPLIST_BYTES(zl)-totlen);
- ZIPLIST_INCR_LENGTH(zl,-deleted);
- }
- return zl;
+ unsigned char *p = ziplistIndex(zl,index);
+ return __ziplistDelete(zl,p,num);
}
/* Delete a single entry from the ziplist, pointed to by *p.
* Also update *p in place, to be able to iterate over the
* ziplist, while deleting entries. */
unsigned char *ziplistDelete(unsigned char *zl, unsigned char **p) {
- unsigned int offset = *p-zl, tail, len;
- len = zipRawEntryLength(*p);
- tail = ZIPLIST_BYTES(zl)-offset-len-1;
-
- /* Move current tail to the new tail when there *is* a tail */
- if (tail > 0) memmove(*p,*p+len,tail);
+ unsigned int offset = *p-zl;
+ zl = __ziplistDelete(zl,*p,1);
- /* Resize and update length */
- zl = ziplistResize(zl, ZIPLIST_BYTES(zl)-len);
- ZIPLIST_INCR_LENGTH(zl,-1);
-
- /* Store new pointer to current element in p.
- * This needs to be done because zl can change on realloc. */
+ /* Store pointer to current element in p, because ziplistDelete will
+ * do a realloc which might result in a different "zl"-pointer. */
*p = zl+offset;
return zl;
}
/* Compare entry pointer to by 'p' with 'entry'. Return 1 if equal. */
-unsigned int ziplistCompare(unsigned char *p, unsigned char *entry, unsigned int elen) {
- unsigned int zlen, lensize;
- char encoding;
- long long zval, eval;
+unsigned int ziplistCompare(unsigned char *p, unsigned char *sstr, unsigned int slen) {
+ zlentry entry;
+ unsigned char sencoding;
+ long long val, sval;
if (*p == ZIP_END) return 0;
- zlen = zipDecodeLength(p,&lensize);
- if (ZIP_ENCODING(p) == ZIP_ENC_RAW) {
+ entry = zipEntry(p);
+ if (entry.encoding == ZIP_ENC_RAW) {
/* Raw compare */
- if (zlen == elen) {
- return memcmp(p+lensize,entry,elen) == 0;
+ if (entry.len == slen) {
+ return memcmp(p+entry.headersize,sstr,slen) == 0;
} else {
return 0;
}
} else {
- if (zipTryEncoding(entry,&eval,&encoding)) {
- /* Do integer compare */
- zval = zipLoadInteger(p+lensize,ZIP_ENCODING(p));
- return zval == eval;
- } else {
- /* Ziplist entry is integer encoded, but given entry is not. */
+ /* Try to compare encoded values */
+ if (zipTryEncoding(sstr,&sval,&sencoding)) {
+ if (entry.encoding == sencoding) {
+ val = zipLoadInteger(p+entry.headersize,entry.encoding);
+ return val == sval;
+ }
}
}
return 0;
}
void ziplistRepr(unsigned char *zl) {
- unsigned char *p, encoding;
- unsigned int l, lsize;
- long long value;
+ unsigned char *p;
+ zlentry entry;
printf("{total bytes %d} {length %u}\n",ZIPLIST_BYTES(zl), ZIPLIST_LENGTH(zl));
p = ziplistHead(zl);
while(*p != ZIP_END) {
- l = zipDecodeLength(p,&lsize);
- printf("{header %u, payload %u} ",lsize,l);
- encoding = ZIP_ENCODING(p);
- p += lsize;
- if (encoding == ZIP_ENC_RAW) {
- fwrite(p,l,1,stdout);
+ entry = zipEntry(p);
+ printf("{offset %ld, header %u, payload %u} ",p-zl,entry.headersize,entry.len);
+ p += entry.headersize;
+ if (entry.encoding == ZIP_ENC_RAW) {
+ fwrite(p,entry.len,1,stdout);
} else {
- printf("%lld", zipLoadInteger(p,encoding));
+ printf("%lld", zipLoadInteger(p,entry.encoding));
}
printf("\n");
- p += l;
+ p += entry.len;
}
printf("{end}\n\n");
}
printf("Pop head: %s (length %ld)\n", s, sdslen(s));
ziplistRepr(zl);
+ zl = ziplistPop(zl, &s, ZIPLIST_TAIL);
+ printf("Pop tail: %s (length %ld)\n", s, sdslen(s));
+ ziplistRepr(zl);
+
+ zl = ziplistPop(zl, &s, ZIPLIST_TAIL);
+ printf("Pop tail: %s (length %ld)\n", s, sdslen(s));
+ ziplistRepr(zl);
+
printf("Iterate list from 0 to end:\n");
{
zl = createList();
zl = createList();
p = ziplistIndex(zl, 0);
if (!ziplistCompare(p,"hello",5)) {
- printf("ERROR\n");
+ printf("ERROR: not \"hello\"\n");
return;
}
if (ziplistCompare(p,"hella",5)) {
- printf("ERROR\n");
+ printf("ERROR: \"hella\"\n");
return;
}
p = ziplistIndex(zl, 3);
if (!ziplistCompare(p,"1024",4)) {
- printf("ERROR\n");
+ printf("ERROR: not \"1024\"\n");
return;
}
if (ziplistCompare(p,"1025",4)) {
- printf("ERROR\n");
+ printf("ERROR: \"1025\"\n");
return;
}
printf("SUCCESS\n");
projects / redis.git / blobdiff