#include <assert.h>
#include "zmalloc.h"
-#define ZIPMAP_BIGLEN 253
-#define ZIPMAP_EMPTY 254
+#define ZIPMAP_BIGLEN 254
#define ZIPMAP_END 255
-#define ZIPMAP_STATUS_FRAGMENTED 1
-
/* The following defines the max value for the <free> field described in the
* comments above, that is, the max number of trailing bytes in a value. */
#define ZIPMAP_VALUE_MAX_FREE 5
unsigned char *zipmapNew(void) {
unsigned char *zm = zmalloc(2);
- zm[0] = 0; /* Status */
+ zm[0] = 0; /* Length */
zm[1] = ZIPMAP_END;
return zm;
}
*
* If NULL is returned, and totlen is not NULL, it is set to the entire
* size of the zimap, so that the calling function will be able to
- * reallocate the original zipmap to make room for more entries.
- *
- * If NULL is returned, and freeoff and freelen are not NULL, they are set
- * to the offset of the first empty space that can hold '*freelen' bytes
- * (freelen is an integer pointer used both to signal the required length
- * and to get the reply from the function). If there is not a suitable
- * free space block to hold the requested bytes, *freelen is set to 0. */
-static unsigned char *zipmapLookupRaw(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned int *totlen, unsigned int *freeoff, unsigned int *freelen) {
- unsigned char *p = zm+1;
+ * reallocate the original zipmap to make room for more entries. */
+static unsigned char *zipmapLookupRaw(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned int *totlen) {
+ unsigned char *p = zm+1, *k = NULL;
unsigned int l;
- unsigned int reqfreelen = 0; /* initialized just to prevent warning */
- if (freelen) {
- reqfreelen = *freelen;
- *freelen = 0;
- assert(reqfreelen != 0);
- }
while(*p != ZIPMAP_END) {
- if (*p == ZIPMAP_EMPTY) {
- l = zipmapDecodeLength(p+1);
- /* if the user want a free space report, and this space is
- * enough, and we did't already found a suitable space... */
- if (freelen && l >= reqfreelen && *freelen == 0) {
- *freelen = l;
- *freeoff = p-zm;
+ unsigned char free;
+
+ /* Match or skip the key */
+ l = zipmapDecodeLength(p);
+ if (k == NULL && l == klen && !memcmp(p+1,key,l)) {
+ /* Only return when the user doesn't care
+ * for the total length of the zipmap. */
+ if (totlen != NULL) {
+ k = p;
+ } else {
+ return p;
}
- p += l;
- zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
- } else {
- unsigned char free;
-
- /* Match or skip the key */
- l = zipmapDecodeLength(p);
- if (l == klen && !memcmp(p+1,key,l)) return p;
- p += zipmapEncodeLength(NULL,l) + l;
- /* Skip the value as well */
- l = zipmapDecodeLength(p);
- p += zipmapEncodeLength(NULL,l);
- free = p[0];
- p += l+1+free; /* +1 to skip the free byte */
}
+ p += zipmapEncodeLength(NULL,l) + l;
+ /* Skip the value as well */
+ l = zipmapDecodeLength(p);
+ p += zipmapEncodeLength(NULL,l);
+ free = p[0];
+ p += l+1+free; /* +1 to skip the free byte */
}
if (totlen != NULL) *totlen = (unsigned int)(p-zm)+1;
- return NULL;
+ return k;
}
static unsigned long zipmapRequiredLength(unsigned int klen, unsigned int vlen) {
* free space if any). */
static unsigned int zipmapRawEntryLength(unsigned char *p) {
unsigned int l = zipmapRawKeyLength(p);
-
return l + zipmapRawValueLength(p+l);
}
+static inline unsigned char *zipmapResize(unsigned char *zm, unsigned int len) {
+ zm = zrealloc(zm, len);
+ zm[len-1] = ZIPMAP_END;
+ return zm;
+}
+
/* Set key to value, creating the key if it does not already exist.
* If 'update' is not NULL, *update is set to 1 if the key was
* already preset, otherwise to 0. */
unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned char *val, unsigned int vlen, int *update) {
- unsigned int oldlen = 0, freeoff = 0, freelen;
- unsigned int reqlen = zipmapRequiredLength(klen,vlen);
+ unsigned int zmlen;
+ unsigned int freelen, reqlen = zipmapRequiredLength(klen,vlen);
unsigned int empty, vempty;
unsigned char *p;
freelen = reqlen;
if (update) *update = 0;
- p = zipmapLookupRaw(zm,key,klen,&oldlen,&freeoff,&freelen);
- if (p == NULL && freelen == 0) {
- /* Key not found, and not space for the new key. Enlarge */
- zm = zrealloc(zm,oldlen+reqlen);
- p = zm+oldlen-1;
- zm[oldlen+reqlen-1] = ZIPMAP_END;
- freelen = reqlen;
- } else if (p == NULL) {
- /* Key not found, but there is enough free space. */
- p = zm+freeoff;
- /* note: freelen is already set in this case */
- } else {
- unsigned char *b = p;
+ p = zipmapLookupRaw(zm,key,klen,&zmlen);
+ if (p == NULL) {
+ /* Key not found: enlarge */
+ zm = zipmapResize(zm, zmlen+reqlen);
+ p = zm+zmlen-1;
+ zmlen = zmlen+reqlen;
+ /* Increase zipmap length (this is an insert) */
+ if (zm[0] < ZIPMAP_BIGLEN) zm[0]++;
+ } else {
/* Key found. Is there enough space for the new value? */
/* Compute the total length: */
if (update) *update = 1;
- freelen = zipmapRawKeyLength(b);
- b += freelen;
- freelen += zipmapRawValueLength(b);
+ freelen = zipmapRawEntryLength(p);
if (freelen < reqlen) {
- /* Mark this entry as free and recurse */
- p[0] = ZIPMAP_EMPTY;
- zipmapEncodeLength(p+1,freelen);
- zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
- return zipmapSet(zm,key,klen,val,vlen,NULL);
+ /* Move remaining entries to the current position, so this
+ * pair can be appended. Note: the +1 in memmove is caused
+ * by the end-of-zipmap byte. */
+ memmove(p, p+freelen, zmlen-((p-zm)+freelen+1));
+ zm = zipmapResize(zm, zmlen-freelen+reqlen);
+ p = zm+zmlen-1-freelen;
+ zmlen = zmlen-1-freelen+reqlen;
+ freelen = reqlen;
}
}
/* If there is too much free space mark it as a free block instead
* of adding it as trailing empty space for the value, as we want
* zipmaps to be very space efficient. */
- if (empty > ZIPMAP_VALUE_MAX_FREE) {
- unsigned char *e;
-
- e = p+reqlen;
- e[0] = ZIPMAP_EMPTY;
- zipmapEncodeLength(e+1,empty);
+ if (empty >= ZIPMAP_VALUE_MAX_FREE) {
+ memmove(p+reqlen, p+freelen, zmlen-((p-zm)+freelen+1));
+ zmlen -= empty;
+ zm = zipmapResize(zm, zmlen);
vempty = 0;
- zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
} else {
vempty = empty;
}
/* Remove the specified key. If 'deleted' is not NULL the pointed integer is
* set to 0 if the key was not found, to 1 if it was found and deleted. */
unsigned char *zipmapDel(unsigned char *zm, unsigned char *key, unsigned int klen, int *deleted) {
- unsigned char *p = zipmapLookupRaw(zm,key,klen,NULL,NULL,NULL);
+ unsigned int zmlen, freelen;
+ unsigned char *p = zipmapLookupRaw(zm,key,klen,&zmlen);
if (p) {
- unsigned int freelen = zipmapRawEntryLength(p);
+ freelen = zipmapRawEntryLength(p);
+ memmove(p, p+freelen, zmlen-((p-zm)+freelen+1));
+ zm = zipmapResize(zm, zmlen-freelen);
+
+ /* Decrease zipmap length */
+ if (zm[0] < ZIPMAP_BIGLEN) zm[0]--;
- p[0] = ZIPMAP_EMPTY;
- zipmapEncodeLength(p+1,freelen);
- zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
if (deleted) *deleted = 1;
} else {
if (deleted) *deleted = 0;
* }
*/
unsigned char *zipmapNext(unsigned char *zm, unsigned char **key, unsigned int *klen, unsigned char **value, unsigned int *vlen) {
- while(zm[0] == ZIPMAP_EMPTY)
- zm += zipmapDecodeLength(zm+1);
if (zm[0] == ZIPMAP_END) return NULL;
if (key) {
*key = zm;
int zipmapGet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned char **value, unsigned int *vlen) {
unsigned char *p;
- if ((p = zipmapLookupRaw(zm,key,klen,NULL,NULL,NULL)) == NULL) return 0;
+ if ((p = zipmapLookupRaw(zm,key,klen,NULL)) == NULL) return 0;
p += zipmapRawKeyLength(p);
*vlen = zipmapDecodeLength(p);
*value = p + ZIPMAP_LEN_BYTES(*vlen) + 1;
/* Return 1 if the key exists, otherwise 0 is returned. */
int zipmapExists(unsigned char *zm, unsigned char *key, unsigned int klen) {
- return zipmapLookupRaw(zm,key,klen,NULL,NULL,NULL) != NULL;
+ return zipmapLookupRaw(zm,key,klen,NULL) != NULL;
}
/* Return the number of entries inside a zipmap */
unsigned int zipmapLen(unsigned char *zm) {
- unsigned char *p = zipmapRewind(zm);
unsigned int len = 0;
+ if (zm[0] < ZIPMAP_BIGLEN) {
+ len = zm[0];
+ } else {
+ unsigned char *p = zipmapRewind(zm);
+ while((p = zipmapNext(p,NULL,NULL,NULL,NULL)) != NULL) len++;
- while((p = zipmapNext(p,NULL,NULL,NULL,NULL)) != NULL) len++;
+ /* Re-store length if small enough */
+ if (len < ZIPMAP_BIGLEN) zm[0] = len;
+ }
return len;
}
if (p[0] == ZIPMAP_END) {
printf("{end}");
break;
- } else if (p[0] == ZIPMAP_EMPTY) {
- l = zipmapDecodeLength(p+1);
- printf("{%u empty block}", l);
- p += l;
} else {
unsigned char e;
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