*
* The most compact representation of the above two elements hash is actually:
*
- * "\x00\x03\x00foo\x03\x00bar\x05\x00hello\x05\x00world\xff"
+ * "\x00\x03foo\x03\x00bar\x05hello\x05\x00world\xff"
*
* Empty space is marked using a 254 bytes + a <len> (coded as already
* specified). The length includes the 254 bytes in the count and the
* space taken by the <len> field. So for instance removing the "foo" key
* from the zipmap above will lead to the following representation:
*
- * "\xfd\x10........\x05\x00hello\x05\x00world\xff"
+ * "\x00\xfd\x10........\x05hello\x05\x00world\xff"
*
* Note that because empty space, keys, values, are all prefixed length
* "objects", the lookup will take O(N) where N is the numeber of elements
* comments above, that is, the max number of trailing bytes in a value. */
#define ZIPMAP_VALUE_MAX_FREE 5
+/* 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);
unsigned int len = *p;
if (len < ZIPMAP_BIGLEN) return len;
- memcpy(&len,p,sizeof(unsigned int));
+ memcpy(&len,p+1,sizeof(unsigned int));
return len;
}
* the amount of bytes required to encode such a length. */
static unsigned int zipmapEncodeLength(unsigned char *p, unsigned int len) {
if (p == NULL) {
- return (len < ZIPMAP_BIGLEN) ? 1 : 1+sizeof(unsigned int);
+ return ZIPMAP_LEN_BYTES(len);
} else {
if (len < ZIPMAP_BIGLEN) {
p[0] = len;
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;
unsigned int l;
- unsigned int reqfreelen;
+ unsigned int reqfreelen = 0; /* initialized just to prevent warning */
if (freelen) {
reqfreelen = *freelen;
return l;
}
-/* Return the total amonut used by a key (encoded length + payload) */
+/* Return the total amount used by a key (encoded length + payload) */
static unsigned int zipmapRawKeyLength(unsigned char *p) {
unsigned int l = zipmapDecodeLength(p);
return zipmapEncodeLength(NULL,l) + l;
}
-/* Return the total amonut used by a value
+/* 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 = zipmapDecodeLength(p);
return used;
}
-/* Set key to value, creating the key if it does not already exist. */
-unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned char *val, unsigned int vlen) {
+/* If 'p' points to a key, this function returns the total amount of
+ * bytes used to store this entry (entry = key + associated value + trailing
+ * free space if any). */
+static unsigned int zipmapRawEntryLength(unsigned char *p) {
+ unsigned int l = zipmapRawKeyLength(p);
+
+ return l + zipmapRawValueLength(p+l);
+}
+
+/* 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 empty, vempty;
unsigned char *p;
freelen = reqlen;
+ if (update) *update = 0;
p = zipmapLookupRaw(zm,key,klen,&oldlen,&freeoff,&freelen);
if (p == NULL && freelen == 0) {
- printf("HERE oldlen:%u required:%u\n",oldlen,reqlen);
/* 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;
- printf("New total length is: %u\n", oldlen+reqlen);
} else if (p == NULL) {
/* Key not found, but there is enough free space. */
p = zm+freeoff;
/* 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);
if (freelen < reqlen) {
- /* Mark this blog as free and recurse */
+ /* Mark this entry as free and recurse */
p[0] = ZIPMAP_EMPTY;
zipmapEncodeLength(p+1,freelen);
- return zipmapSet(zm,key,klen,val,vlen);
+ zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
+ return zipmapSet(zm,key,klen,val,vlen,NULL);
}
}
return zm;
}
+/* 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);
+ if (p) {
+ unsigned int freelen = zipmapRawEntryLength(p);
+
+ p[0] = ZIPMAP_EMPTY;
+ zipmapEncodeLength(p+1,freelen);
+ zm[0] |= ZIPMAP_STATUS_FRAGMENTED;
+ if (deleted) *deleted = 1;
+ } else {
+ if (deleted) *deleted = 0;
+ }
+ return zm;
+}
+
+/* Call it before to iterate trought elements via zipmapNext() */
+unsigned char *zipmapRewind(unsigned char *zm) {
+ return zm+1;
+}
+
+/* This function is used to iterate through all the zipmap elements.
+ * In the first call the first argument is the pointer to the zipmap + 1.
+ * In the next calls what zipmapNext returns is used as first argument.
+ * Example:
+ *
+ * unsigned char *i = zipmapRewind(my_zipmap);
+ * while((i = zipmapNext(i,&key,&klen,&value,&vlen)) != NULL) {
+ * printf("%d bytes key at $p\n", klen, key);
+ * printf("%d bytes value at $p\n", vlen, value);
+ * }
+ */
+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;
+ *klen = zipmapDecodeLength(zm);
+ *key += ZIPMAP_LEN_BYTES(*klen);
+ }
+ zm += zipmapRawKeyLength(zm);
+ if (value) {
+ *value = zm+1;
+ *vlen = zipmapDecodeLength(zm);
+ *value += ZIPMAP_LEN_BYTES(*vlen);
+ }
+ zm += zipmapRawValueLength(zm);
+ return zm;
+}
+
+/* Search a key and retrieve the pointer and len of the associated value.
+ * If the key is found the function returns 1, otherwise 0. */
+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;
+ p += zipmapRawKeyLength(p);
+ *vlen = zipmapDecodeLength(p);
+ *value = p + ZIPMAP_LEN_BYTES(*vlen) + 1;
+ return 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 the number of entries inside a zipmap */
+unsigned int zipmapLen(unsigned char *zm) {
+ unsigned char *p = zipmapRewind(zm);
+ unsigned int len = 0;
+
+ while((p = zipmapNext(p,NULL,NULL,NULL,NULL)) != NULL) len++;
+ return len;
+}
+
void zipmapRepr(unsigned char *p) {
unsigned int l;
p += zipmapEncodeLength(NULL,l);
e = *p++;
fwrite(p,l,1,stdout);
- p += l;
+ p += l+e;
if (e) {
printf("[");
while(e--) printf(".");
printf("\n");
}
+#ifdef ZIPMAP_TEST_MAIN
int main(void) {
unsigned char *zm;
zm = zipmapNew();
- zm = zipmapSet(zm,(unsigned char*) "hello",5, (unsigned char*) "world!",6);
- zm = zipmapSet(zm,(unsigned char*) "foo",3, (unsigned char*) "bar",3);
+
+ zm = zipmapSet(zm,(unsigned char*) "name",4, (unsigned char*) "foo",3,NULL);
+ zm = zipmapSet(zm,(unsigned char*) "surname",7, (unsigned char*) "foo",3,NULL);
+ zm = zipmapSet(zm,(unsigned char*) "age",3, (unsigned char*) "foo",3,NULL);
zipmapRepr(zm);
+ exit(1);
+
+ zm = zipmapSet(zm,(unsigned char*) "hello",5, (unsigned char*) "world!",6,NULL);
+ zm = zipmapSet(zm,(unsigned char*) "foo",3, (unsigned char*) "bar",3,NULL);
+ zm = zipmapSet(zm,(unsigned char*) "foo",3, (unsigned char*) "!",1,NULL);
+ zipmapRepr(zm);
+ zm = zipmapSet(zm,(unsigned char*) "foo",3, (unsigned char*) "12345",5,NULL);
+ zipmapRepr(zm);
+ zm = zipmapSet(zm,(unsigned char*) "new",3, (unsigned char*) "xx",2,NULL);
+ zm = zipmapSet(zm,(unsigned char*) "noval",5, (unsigned char*) "",0,NULL);
+ zipmapRepr(zm);
+ zm = zipmapDel(zm,(unsigned char*) "new",3,NULL);
+ zipmapRepr(zm);
+ printf("\nPerform a direct lookup:\n");
+ {
+ unsigned char *value;
+ unsigned int vlen;
+
+ if (zipmapGet(zm,(unsigned char*) "foo",3,&value,&vlen)) {
+ printf(" foo is associated to the %d bytes value: %.*s\n",
+ vlen, vlen, value);
+ }
+ }
+ printf("\nIterate trought elements:\n");
+ {
+ unsigned char *i = zipmapRewind(zm);
+ unsigned char *key, *value;
+ unsigned int klen, vlen;
+
+ while((i = zipmapNext(i,&key,&klen,&value,&vlen)) != NULL) {
+ printf(" %d:%.*s => %d:%.*s\n", klen, klen, key, vlen, vlen, value);
+ }
+ }
return 0;
}
+#endif
projects / redis.git / blobdiff