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https://github.com/fluencelabs/redis
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implemented strategy that doesn't use free blocks in zipmaps
This commit is contained in:
Pieter Noordhuis
parent
570e43c828
commit
43078ff844
114
zipmap.c
114
zipmap.c
@ -149,43 +149,33 @@ static unsigned int zipmapEncodeLength(unsigned char *p, unsigned int len) {
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* (freelen is an integer pointer used both to signal the required length
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* and to get the reply from the function). If there is not a suitable
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* free space block to hold the requested bytes, *freelen is set to 0. */
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static unsigned char *zipmapLookupRaw(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned int *totlen, unsigned int *freeoff, unsigned int *freelen) {
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unsigned char *p = zm+1;
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static unsigned char *zipmapLookupRaw(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned int *totlen) {
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unsigned char *p = zm+1, *k = NULL;
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unsigned int l;
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unsigned int reqfreelen = 0; /* initialized just to prevent warning */
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if (freelen) {
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reqfreelen = *freelen;
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*freelen = 0;
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assert(reqfreelen != 0);
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}
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while(*p != ZIPMAP_END) {
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if (*p == ZIPMAP_EMPTY) {
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l = zipmapDecodeLength(p+1);
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/* if the user want a free space report, and this space is
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* enough, and we did't already found a suitable space... */
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if (freelen && l >= reqfreelen && *freelen == 0) {
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*freelen = l;
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*freeoff = p-zm;
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}
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p += l;
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zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
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} else {
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unsigned char free;
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unsigned char free;
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/* Match or skip the key */
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l = zipmapDecodeLength(p);
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if (l == klen && !memcmp(p+1,key,l)) return p;
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p += zipmapEncodeLength(NULL,l) + l;
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/* Skip the value as well */
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l = zipmapDecodeLength(p);
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p += zipmapEncodeLength(NULL,l);
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free = p[0];
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p += l+1+free; /* +1 to skip the free byte */
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/* Match or skip the key */
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l = zipmapDecodeLength(p);
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if (k == NULL && l == klen && !memcmp(p+1,key,l)) {
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/* Only return when the user doesn't care
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* for the total length of the zipmap. */
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if (totlen != NULL) {
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k = p;
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} else {
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return p;
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}
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}
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p += zipmapEncodeLength(NULL,l) + l;
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/* Skip the value as well */
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l = zipmapDecodeLength(p);
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p += zipmapEncodeLength(NULL,l);
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free = p[0];
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p += l+1+free; /* +1 to skip the free byte */
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}
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if (totlen != NULL) *totlen = (unsigned int)(p-zm)+1;
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return NULL;
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return k;
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}
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static unsigned long zipmapRequiredLength(unsigned int klen, unsigned int vlen) {
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@ -224,28 +214,29 @@ static unsigned int zipmapRawEntryLength(unsigned char *p) {
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return l + zipmapRawValueLength(p+l);
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}
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static inline unsigned char *zipmapResize(unsigned char *zm, unsigned int len) {
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zm = zrealloc(zm, len);
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zm[len-1] = ZIPMAP_END;
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return zm;
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}
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/* Set key to value, creating the key if it does not already exist.
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* If 'update' is not NULL, *update is set to 1 if the key was
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* already preset, otherwise to 0. */
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unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned char *val, unsigned int vlen, int *update) {
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unsigned int oldlen = 0, freeoff = 0, freelen;
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unsigned int reqlen = zipmapRequiredLength(klen,vlen);
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unsigned int zmlen;
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unsigned int freelen, reqlen = zipmapRequiredLength(klen,vlen);
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unsigned int empty, vempty;
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unsigned char *p;
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freelen = reqlen;
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if (update) *update = 0;
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p = zipmapLookupRaw(zm,key,klen,&oldlen,&freeoff,&freelen);
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if (p == NULL && freelen == 0) {
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/* Key not found, and not space for the new key. Enlarge */
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zm = zrealloc(zm,oldlen+reqlen);
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p = zm+oldlen-1;
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zm[oldlen+reqlen-1] = ZIPMAP_END;
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freelen = reqlen;
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} else if (p == NULL) {
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/* Key not found, but there is enough free space. */
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p = zm+freeoff;
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/* note: freelen is already set in this case */
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p = zipmapLookupRaw(zm,key,klen,&zmlen);
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if (p == NULL) {
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/* Key not found: enlarge */
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zm = zipmapResize(zm, zmlen+reqlen);
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p = zm+zmlen-1;
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zmlen = zmlen+reqlen;
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} else {
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unsigned char *b = p;
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@ -256,11 +247,14 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
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b += freelen;
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freelen += zipmapRawValueLength(b);
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if (freelen < reqlen) {
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/* Mark this entry as free and recurse */
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p[0] = ZIPMAP_EMPTY;
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zipmapEncodeLength(p+1,freelen);
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zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
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return zipmapSet(zm,key,klen,val,vlen,NULL);
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/* Move remaining entries to the current position, so this
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* pair can be appended. Note: the +1 in memmove is caused
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* by the end-of-zipmap byte. */
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memmove(p, p+freelen, zmlen-((p-zm)+freelen+1));
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zm = zipmapResize(zm, zmlen-freelen+reqlen);
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p = zm+zmlen-1-freelen;
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zmlen = zmlen-1-freelen+reqlen;
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freelen = reqlen;
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}
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}
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@ -270,14 +264,11 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
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/* If there is too much free space mark it as a free block instead
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* of adding it as trailing empty space for the value, as we want
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* zipmaps to be very space efficient. */
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if (empty > ZIPMAP_VALUE_MAX_FREE) {
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unsigned char *e;
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e = p+reqlen;
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e[0] = ZIPMAP_EMPTY;
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zipmapEncodeLength(e+1,empty);
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if (empty >= ZIPMAP_VALUE_MAX_FREE) {
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memmove(p+reqlen, p+freelen, zmlen-((p-zm)+freelen+1));
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zmlen -= empty;
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zm = zipmapResize(zm, zmlen);
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vempty = 0;
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zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
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} else {
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vempty = empty;
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}
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@ -297,13 +288,12 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
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/* Remove the specified key. If 'deleted' is not NULL the pointed integer is
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* set to 0 if the key was not found, to 1 if it was found and deleted. */
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unsigned char *zipmapDel(unsigned char *zm, unsigned char *key, unsigned int klen, int *deleted) {
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unsigned char *p = zipmapLookupRaw(zm,key,klen,NULL,NULL,NULL);
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unsigned int zmlen;
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unsigned char *p = zipmapLookupRaw(zm,key,klen,&zmlen);
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if (p) {
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unsigned int freelen = zipmapRawEntryLength(p);
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p[0] = ZIPMAP_EMPTY;
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zipmapEncodeLength(p+1,freelen);
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zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
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memmove(p, p+freelen, zmlen-((p-zm)+freelen+1));
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zm = zipmapResize(zm, zmlen-freelen);
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if (deleted) *deleted = 1;
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} else {
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if (deleted) *deleted = 0;
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@ -351,7 +341,7 @@ unsigned char *zipmapNext(unsigned char *zm, unsigned char **key, unsigned int *
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int zipmapGet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned char **value, unsigned int *vlen) {
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unsigned char *p;
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if ((p = zipmapLookupRaw(zm,key,klen,NULL,NULL,NULL)) == NULL) return 0;
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if ((p = zipmapLookupRaw(zm,key,klen,NULL)) == NULL) return 0;
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p += zipmapRawKeyLength(p);
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*vlen = zipmapDecodeLength(p);
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*value = p + ZIPMAP_LEN_BYTES(*vlen) + 1;
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@ -360,7 +350,7 @@ int zipmapGet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned
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/* Return 1 if the key exists, otherwise 0 is returned. */
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int zipmapExists(unsigned char *zm, unsigned char *key, unsigned int klen) {
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return zipmapLookupRaw(zm,key,klen,NULL,NULL,NULL) != NULL;
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return zipmapLookupRaw(zm,key,klen,NULL) != NULL;
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}
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/* Return the number of entries inside a zipmap */
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