use function to determine length of a single entry

[redis.git] / zipmap.c

diff --git a/zipmap.c b/zipmap.c
index 5f024dfa6cb732abf1b25cd3321ffdc148dddc38..8a07b388ed5aabb6af3cd83a4bc175d1a6bf6f7b 100644 (file)
--- a/zipmap.c
+++ b/zipmap.c
@@ -87,12 +87,9 @@
 #include <assert.h>
 #include "zmalloc.h"
 
 #include <assert.h>
 #include "zmalloc.h"
 

-#define ZIPMAP_BIGLEN 253
-#define ZIPMAP_EMPTY 254
+#define ZIPMAP_BIGLEN 254

 #define ZIPMAP_END 255
 
 #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
 /* 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


@@ -106,7 +103,7 @@
 unsigned char *zipmapNew(void) {
     unsigned char *zm = zmalloc(2);
 
 unsigned char *zipmapNew(void) {
     unsigned char *zm = zmalloc(2);
 

-    zm[0] = 0; /* Status */
+    zm[0] = 0; /* Length */

     zm[1] = ZIPMAP_END;
     return zm;
 }
     zm[1] = ZIPMAP_END;
     return zm;
 }


@@ -116,7 +113,7 @@ static unsigned int zipmapDecodeLength(unsigned char *p) {
     unsigned int len = *p;
 
     if (len < ZIPMAP_BIGLEN) return len;
     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;
 }
 
     return len;
 }
 


@@ -142,50 +139,34 @@ static unsigned int zipmapEncodeLength(unsigned char *p, unsigned int len) {
  *
  * 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
  *
  * 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 l;

-    unsigned int reqfreelen = 0; /* initialized just to prevent warning */

 
 

-    if (freelen) {
-        reqfreelen = *freelen;
-        *freelen = 0;
-        assert(reqfreelen != 0);
-    }

     while(*p != ZIPMAP_END) {
     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;
     }
     if (totlen != NULL) *totlen = (unsigned int)(p-zm)+1;

-    return NULL;
+    return k;

 }
 
 static unsigned long zipmapRequiredLength(unsigned int klen, unsigned int vlen) {
 }
 
 static unsigned long zipmapRequiredLength(unsigned int klen, unsigned int vlen) {


@@ -220,47 +201,49 @@ static unsigned int zipmapRawValueLength(unsigned char *p) {
  * free space if any). */
 static unsigned int zipmapRawEntryLength(unsigned char *p) {
     unsigned int l = zipmapRawKeyLength(p);
  * free space if any). */
 static unsigned int zipmapRawEntryLength(unsigned char *p) {
     unsigned int l = zipmapRawKeyLength(p);

-

     return l + zipmapRawValueLength(p+l);
 }
 
     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) {
 /* 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;
     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;
         /* 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) {
         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;

         }
     }
 
         }
     }
 


@@ -270,14 +253,11 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
     /* 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 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;
         vempty = 0;

-        zm[0] |= ZIPMAP_STATUS_FRAGMENTED;

     } else {
         vempty = empty;
     }
     } else {
         vempty = empty;
     }


@@ -297,13 +277,16 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
 /* 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) {
 /* 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) {
     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;
         if (deleted) *deleted = 1;
     } else {
         if (deleted) *deleted = 0;


@@ -328,8 +311,6 @@ unsigned char *zipmapRewind(unsigned char *zm) {
  * }
  */
 unsigned char *zipmapNext(unsigned char *zm, unsigned char **key, unsigned int *klen, unsigned char **value, unsigned int *vlen) {
  * }
  */
 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;
     if (zm[0] == ZIPMAP_END) return NULL;
     if (key) {
         *key = zm;


@@ -351,7 +332,7 @@ unsigned char *zipmapNext(unsigned char *zm, unsigned char **key, unsigned int *
 int zipmapGet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned char **value, unsigned int *vlen) {
     unsigned char *p;
 
 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;
     p += zipmapRawKeyLength(p);
     *vlen = zipmapDecodeLength(p);
     *value = p + ZIPMAP_LEN_BYTES(*vlen) + 1;


@@ -360,15 +341,21 @@ int zipmapGet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned
 
 /* Return 1 if the key exists, otherwise 0 is returned. */
 int zipmapExists(unsigned char *zm, unsigned char *key, unsigned int klen) {
 
 /* 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) {
 }
 
 /* Return the number of entries inside a zipmap */
 unsigned int zipmapLen(unsigned char *zm) {

-    unsigned char *p = zipmapRewind(zm);

     unsigned int len = 0;
     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;
 }
 
     return len;
 }
 


@@ -380,10 +367,6 @@ void zipmapRepr(unsigned char *p) {
         if (p[0] == ZIPMAP_END) {
             printf("{end}");
             break;
         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;
 
         } else {
             unsigned char e;