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partial revert of c80df5 because ziplist functions are starting to divert too much from zipmap functions

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This commit is contained in:
Pieter Noordhuis 2010-05-22 15:13:09 +02:00
parent 29b14d5fac
commit af5f66fb98
1 changed files with 74 additions and 34 deletions
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108
zipmap.c
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@ -80,21 +80,54 @@
#include <string.h>
#include <assert.h>
#include "zmalloc.h"
#include "zip.c"
#define ZIPMAP_BIGLEN 254
#define ZIPMAP_END 255
/* 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 4
/* The following macro returns the number of bytes needed to encode the length
* for the integer value _l, that is, 1 byte for lengths < ZIPMAP_BIGLEN and
* 5 bytes for all the other lengths. */
#define ZIPMAP_LEN_BYTES(_l) (((_l) < ZIPMAP_BIGLEN) ? 1 : sizeof(unsigned int)+1)
/* Create a new empty zipmap. */
unsigned char *zipmapNew(void) {
unsigned char *zm = zmalloc(2);
zm[0] = 0; /* Length */
zm[1] = ZIP_END;
zm[1] = ZIPMAP_END;
return zm;
}
/* Decode the encoded length pointed by 'p' */
static unsigned int zipmapDecodeLength(unsigned char *p) {
unsigned int len = *p;
if (len < ZIPMAP_BIGLEN) return len;
memcpy(&len,p+1,sizeof(unsigned int));
return len;
}
/* Encode the length 'l' writing it in 'p'. If p is NULL it just returns
* the amount of bytes required to encode such a length. */
static unsigned int zipmapEncodeLength(unsigned char *p, unsigned int len) {
if (p == NULL) {
return ZIPMAP_LEN_BYTES(len);
} else {
if (len < ZIPMAP_BIGLEN) {
p[0] = len;
return 1;
} else {
p[0] = ZIPMAP_BIGLEN;
memcpy(p+1,&len,sizeof(len));
return 1+sizeof(len);
}
}
}
/* Search for a matching key, returning a pointer to the entry inside the
* zipmap. Returns NULL if the key is not found.
*
@ -105,12 +138,12 @@ static unsigned char *zipmapLookupRaw(unsigned char *zm, unsigned char *key, uns
unsigned char *p = zm+1, *k = NULL;
unsigned int l,llen;
while(*p != ZIP_END) {
while(*p != ZIPMAP_END) {
unsigned char free;
/* Match or skip the key */
l = zipDecodeLength(p);
llen = zipEncodeLength(NULL,l);
l = zipmapDecodeLength(p);
llen = zipmapEncodeLength(NULL,l);
if (k == NULL && l == klen && !memcmp(p+llen,key,l)) {
/* Only return when the user doesn't care
* for the total length of the zipmap. */
@ -122,8 +155,8 @@ static unsigned char *zipmapLookupRaw(unsigned char *zm, unsigned char *key, uns
}
p += llen+l;
/* Skip the value as well */
l = zipDecodeLength(p);
p += zipEncodeLength(NULL,l);
l = zipmapDecodeLength(p);
p += zipmapEncodeLength(NULL,l);
free = p[0];
p += l+1+free; /* +1 to skip the free byte */
}
@ -135,23 +168,24 @@ static unsigned long zipmapRequiredLength(unsigned int klen, unsigned int vlen)
unsigned int l;
l = klen+vlen+3;
if (klen >= ZIP_BIGLEN) l += 4;
if (vlen >= ZIP_BIGLEN) l += 4;
if (klen >= ZIPMAP_BIGLEN) l += 4;
if (vlen >= ZIPMAP_BIGLEN) l += 4;
return l;
}
/* Return the total amount used by a key (encoded length + payload) */
static unsigned int zipmapRawKeyLength(unsigned char *p) {
return zipRawEntryLength(p);
unsigned int l = zipmapDecodeLength(p);
return zipmapEncodeLength(NULL,l) + l;
}
/* Return the total amount used by a value
* (encoded length + single byte free count + payload) */
static unsigned int zipmapRawValueLength(unsigned char *p) {
unsigned int l = zipDecodeLength(p);
unsigned int l = zipmapDecodeLength(p);
unsigned int used;
used = zipEncodeLength(NULL,l);
used = zipmapEncodeLength(NULL,l);
used += p[used] + 1 + l;
return used;
}
@ -164,6 +198,12 @@ static unsigned int zipmapRawEntryLength(unsigned char *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. */
@ -178,12 +218,12 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
p = zipmapLookupRaw(zm,key,klen,&zmlen);
if (p == NULL) {
/* Key not found: enlarge */
zm = zipResize(zm, zmlen+reqlen);
zm = zipmapResize(zm, zmlen+reqlen);
p = zm+zmlen-1;
zmlen = zmlen+reqlen;
/* Increase zipmap length (this is an insert) */
if (zm[0] < ZIP_BIGLEN) zm[0]++;
if (zm[0] < ZIPMAP_BIGLEN) zm[0]++;
} else {
/* Key found. Is there enough space for the new value? */
/* Compute the total length: */
@ -194,7 +234,7 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
* it can be resized. Then, move the tail backwards so this
* pair fits at the current position. */
offset = p-zm;
zm = zipResize(zm, zmlen-freelen+reqlen);
zm = zipmapResize(zm, zmlen-freelen+reqlen);
p = zm+offset;
/* The +1 in the number of bytes to be moved is caused by the
@ -216,7 +256,7 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
offset = p-zm;
memmove(p+reqlen, p+freelen, zmlen-(offset+freelen+1));
zmlen -= empty;
zm = zipResize(zm, zmlen);
zm = zipmapResize(zm, zmlen);
p = zm+offset;
vempty = 0;
} else {
@ -225,11 +265,11 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
/* Just write the key + value and we are done. */
/* Key: */
p += zipEncodeLength(p,klen);
p += zipmapEncodeLength(p,klen);
memcpy(p,key,klen);
p += klen;
/* Value: */
p += zipEncodeLength(p,vlen);
p += zipmapEncodeLength(p,vlen);
*p++ = vempty;
memcpy(p,val,vlen);
return zm;
@ -243,10 +283,10 @@ unsigned char *zipmapDel(unsigned char *zm, unsigned char *key, unsigned int kle
if (p) {
freelen = zipmapRawEntryLength(p);
memmove(p, p+freelen, zmlen-((p-zm)+freelen+1));
zm = zipResize(zm, zmlen-freelen);
zm = zipmapResize(zm, zmlen-freelen);
/* Decrease zipmap length */
if (zm[0] < ZIP_BIGLEN) zm[0]--;
if (zm[0] < ZIPMAP_BIGLEN) zm[0]--;
if (deleted) *deleted = 1;
} else {
@ -272,17 +312,17 @@ unsigned char *zipmapRewind(unsigned char *zm) {
* }
*/
unsigned char *zipmapNext(unsigned char *zm, unsigned char **key, unsigned int *klen, unsigned char **value, unsigned int *vlen) {
if (zm[0] == ZIP_END) return NULL;
if (zm[0] == ZIPMAP_END) return NULL;
if (key) {
*key = zm;
*klen = zipDecodeLength(zm);
*key += ZIP_LEN_BYTES(*klen);
*klen = zipmapDecodeLength(zm);
*key += ZIPMAP_LEN_BYTES(*klen);
}
zm += zipmapRawKeyLength(zm);
if (value) {
*value = zm+1;
*vlen = zipDecodeLength(zm);
*value += ZIP_LEN_BYTES(*vlen);
*vlen = zipmapDecodeLength(zm);
*value += ZIPMAP_LEN_BYTES(*vlen);
}
zm += zipmapRawValueLength(zm);
return zm;
@ -295,8 +335,8 @@ int zipmapGet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned
if ((p = zipmapLookupRaw(zm,key,klen,NULL)) == NULL) return 0;
p += zipmapRawKeyLength(p);
*vlen = zipDecodeLength(p);
*value = p + ZIP_LEN_BYTES(*vlen) + 1;
*vlen = zipmapDecodeLength(p);
*value = p + ZIPMAP_LEN_BYTES(*vlen) + 1;
return 1;
}
@ -308,14 +348,14 @@ int zipmapExists(unsigned char *zm, unsigned char *key, unsigned int klen) {
/* Return the number of entries inside a zipmap */
unsigned int zipmapLen(unsigned char *zm) {
unsigned int len = 0;
if (zm[0] < ZIP_BIGLEN) {
if (zm[0] < ZIPMAP_BIGLEN) {
len = zm[0];
} else {
unsigned char *p = zipmapRewind(zm);
while((p = zipmapNext(p,NULL,NULL,NULL,NULL)) != NULL) len++;
/* Re-store length if small enough */
if (len < ZIP_BIGLEN) zm[0] = len;
if (len < ZIPMAP_BIGLEN) zm[0] = len;
}
return len;
}
@ -325,21 +365,21 @@ void zipmapRepr(unsigned char *p) {
printf("{status %u}",*p++);
while(1) {
if (p[0] == ZIP_END) {
if (p[0] == ZIPMAP_END) {
printf("{end}");
break;
} else {
unsigned char e;
l = zipDecodeLength(p);
l = zipmapDecodeLength(p);
printf("{key %u}",l);
p += zipEncodeLength(NULL,l);
p += zipmapEncodeLength(NULL,l);
fwrite(p,l,1,stdout);
p += l;
l = zipDecodeLength(p);
l = zipmapDecodeLength(p);
printf("{value %u}",l);
p += zipEncodeLength(NULL,l);
p += zipmapEncodeLength(NULL,l);
e = *p++;
fwrite(p,l,1,stdout);
p += l+e;