A reimplementation of blocking operation internals.

[redis.git] / src / ziplist.c

diff --git a/src/ziplist.c b/src/ziplist.c
index 44d63c7867b4c35bdf63c2e0126a9c08c9cf055a..23bad45c656ac6edf46d532866cf46e01b8c3110 100644 (file)
--- a/src/ziplist.c
+++ b/src/ziplist.c
@@ -52,12 +52,23 @@
  *      String value with length less than or equal to 16383 bytes (14 bits).
  * |10______|qqqqqqqq|rrrrrrrr|ssssssss|tttttttt| - 5 bytes
  *      String value with length greater than or equal to 16384 bytes.
  *      String value with length less than or equal to 16383 bytes (14 bits).
  * |10______|qqqqqqqq|rrrrrrrr|ssssssss|tttttttt| - 5 bytes
  *      String value with length greater than or equal to 16384 bytes.

- * |1100____| - 1 byte
+ * |11000000| - 1 byte

  *      Integer encoded as int16_t (2 bytes).
  *      Integer encoded as int16_t (2 bytes).

- * |1101____| - 1 byte
+ * |11010000| - 1 byte

  *      Integer encoded as int32_t (4 bytes).
  *      Integer encoded as int32_t (4 bytes).

- * |1110____| - 1 byte
+ * |11100000| - 1 byte

  *      Integer encoded as int64_t (8 bytes).
  *      Integer encoded as int64_t (8 bytes).

+ * |11110000| - 1 byte
+ *      Integer encoded as 24 bit signed (3 bytes).
+ * |11111110| - 1 byte
+ *      Integer encoded as 8 bit signed (1 byte).
+ * |1111xxxx| - (with xxxx between 0000 and 1101) immediate 4 bit integer.
+ *      Unsigned integer from 0 to 12. The encoded value is actually from
+ *      1 to 13 because 0000 and 1111 can not be used, so 1 should be
+ *      subtracted from the encoded 4 bit value to obtain the right value.
+ * |11111111| - End of ziplist.
+ *
+ * All the integers are represented in little endian byte order.

  */
 
 #include <stdio.h>
  */
 
 #include <stdio.h>


@@ -67,24 +78,35 @@
 #include <assert.h>
 #include <limits.h>
 #include "zmalloc.h"
 #include <assert.h>
 #include <limits.h>
 #include "zmalloc.h"

+#include "util.h"

 #include "ziplist.h"
 #include "ziplist.h"

-
-int ll2string(char *s, size_t len, long long value);
+#include "endianconv.h"

 
 #define ZIP_END 255
 #define ZIP_BIGLEN 254
 
 /* Different encoding/length possibilities */
 
 #define ZIP_END 255
 #define ZIP_BIGLEN 254
 
 /* Different encoding/length possibilities */

+#define ZIP_STR_MASK 0xc0
+#define ZIP_INT_MASK 0x30

 #define ZIP_STR_06B (0 << 6)
 #define ZIP_STR_14B (1 << 6)
 #define ZIP_STR_32B (2 << 6)
 #define ZIP_INT_16B (0xc0 | 0<<4)
 #define ZIP_INT_32B (0xc0 | 1<<4)
 #define ZIP_INT_64B (0xc0 | 2<<4)
 #define ZIP_STR_06B (0 << 6)
 #define ZIP_STR_14B (1 << 6)
 #define ZIP_STR_32B (2 << 6)
 #define ZIP_INT_16B (0xc0 | 0<<4)
 #define ZIP_INT_32B (0xc0 | 1<<4)
 #define ZIP_INT_64B (0xc0 | 2<<4)

+#define ZIP_INT_24B (0xc0 | 3<<4)
+#define ZIP_INT_8B 0xfe
+/* 4 bit integer immediate encoding */
+#define ZIP_INT_IMM_MASK 0x0f
+#define ZIP_INT_IMM_MIN 0xf1    /* 11110001 */
+#define ZIP_INT_IMM_MAX 0xfd    /* 11111101 */
+#define ZIP_INT_IMM_VAL(v) (v & ZIP_INT_IMM_MASK)
+
+#define INT24_MAX 0x7fffff
+#define INT24_MIN (-INT24_MAX - 1)

 
 

-/* Macro's to determine type */
-#define ZIP_IS_STR(enc) (((enc) & 0xc0) < 0xc0)
-#define ZIP_IS_INT(enc) (!ZIP_IS_STR(enc) && ((enc) & 0x30) < 0x30)
+/* Macro to determine type */
+#define ZIP_IS_STR(enc) (((enc) & ZIP_STR_MASK) < ZIP_STR_MASK)

 
 /* Utility macros */
 #define ZIPLIST_BYTES(zl)       (*((uint32_t*)(zl)))
 
 /* Utility macros */
 #define ZIPLIST_BYTES(zl)       (*((uint32_t*)(zl)))


@@ -92,13 +114,15 @@ int ll2string(char *s, size_t len, long long value);
 #define ZIPLIST_LENGTH(zl)      (*((uint16_t*)((zl)+sizeof(uint32_t)*2)))
 #define ZIPLIST_HEADER_SIZE     (sizeof(uint32_t)*2+sizeof(uint16_t))
 #define ZIPLIST_ENTRY_HEAD(zl)  ((zl)+ZIPLIST_HEADER_SIZE)
 #define ZIPLIST_LENGTH(zl)      (*((uint16_t*)((zl)+sizeof(uint32_t)*2)))
 #define ZIPLIST_HEADER_SIZE     (sizeof(uint32_t)*2+sizeof(uint16_t))
 #define ZIPLIST_ENTRY_HEAD(zl)  ((zl)+ZIPLIST_HEADER_SIZE)

-#define ZIPLIST_ENTRY_TAIL(zl)  ((zl)+ZIPLIST_TAIL_OFFSET(zl))
-#define ZIPLIST_ENTRY_END(zl)   ((zl)+ZIPLIST_BYTES(zl)-1)
+#define ZIPLIST_ENTRY_TAIL(zl)  ((zl)+intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl)))
+#define ZIPLIST_ENTRY_END(zl)   ((zl)+intrev32ifbe(ZIPLIST_BYTES(zl))-1)

 
 /* We know a positive increment can only be 1 because entries can only be
  * pushed one at a time. */
 #define ZIPLIST_INCR_LENGTH(zl,incr) { \
 
 /* We know a positive increment can only be 1 because entries can only be
  * pushed one at a time. */
 #define ZIPLIST_INCR_LENGTH(zl,incr) { \

-    if (ZIPLIST_LENGTH(zl) < UINT16_MAX) ZIPLIST_LENGTH(zl)+=incr; }
+    if (ZIPLIST_LENGTH(zl) < UINT16_MAX) \
+        ZIPLIST_LENGTH(zl) = intrev16ifbe(intrev16ifbe(ZIPLIST_LENGTH(zl))+incr); \
+}

 
 typedef struct zlentry {
     unsigned int prevrawlensize, prevrawlen;
 
 typedef struct zlentry {
     unsigned int prevrawlensize, prevrawlen;


@@ -108,61 +132,27 @@ typedef struct zlentry {
     unsigned char *p;
 } zlentry;
 
     unsigned char *p;
 } zlentry;
 

-/* Return the encoding pointer to by 'p'. */
-static unsigned int zipEntryEncoding(unsigned char *p) {
-    /* String encoding: 2 MSBs */
-    unsigned char b = p[0] & 0xc0;
-    if (b < 0xc0) {
-        return b;
-    } else {
-        /* Integer encoding: 4 MSBs */
-        return p[0] & 0xf0;
-    }
-    assert(NULL);
-    return 0;
-}
+/* Extract the encoding from the byte pointed by 'ptr' and set it into
+ * 'encoding'. */
+#define ZIP_ENTRY_ENCODING(ptr, encoding) do {  \
+    (encoding) = (ptr[0]); \
+    if ((encoding) < ZIP_STR_MASK) (encoding) &= ZIP_STR_MASK; \
+} while(0)

 
 /* Return bytes needed to store integer encoded by 'encoding' */
 static unsigned int zipIntSize(unsigned char encoding) {
     switch(encoding) {
 
 /* Return bytes needed to store integer encoded by 'encoding' */
 static unsigned int zipIntSize(unsigned char encoding) {
     switch(encoding) {

-    case ZIP_INT_16B: return sizeof(int16_t);
-    case ZIP_INT_32B: return sizeof(int32_t);
-    case ZIP_INT_64B: return sizeof(int64_t);
+    case ZIP_INT_8B:  return 1;
+    case ZIP_INT_16B: return 2;
+    case ZIP_INT_24B: return 3;
+    case ZIP_INT_32B: return 4;
+    case ZIP_INT_64B: return 8;
+    default: return 0; /* 4 bit immediate */

     }
     assert(NULL);
     return 0;
 }
 
     }
     assert(NULL);
     return 0;
 }
 

-/* Decode the encoded length pointed by 'p'. If a pointer to 'lensize' is
- * provided, it is set to the number of bytes required to encode the length. */
-static unsigned int zipDecodeLength(unsigned char *p, unsigned int *lensize) {
-    unsigned char encoding = zipEntryEncoding(p);
-    unsigned int len = 0;
-
-    if (ZIP_IS_STR(encoding)) {
-        switch(encoding) {
-        case ZIP_STR_06B:
-            len = p[0] & 0x3f;
-            if (lensize) *lensize = 1;
-            break;
-        case ZIP_STR_14B:
-            len = ((p[0] & 0x3f) << 8) | p[1];
-            if (lensize) *lensize = 2;
-            break;
-        case ZIP_STR_32B:
-            len = (p[1] << 24) | (p[2] << 16) | (p[3] << 8) | p[4];
-            if (lensize) *lensize = 5;
-            break;
-        default:
-            assert(NULL);
-        }
-    } else {
-        len = zipIntSize(encoding);
-        if (lensize) *lensize = 1;
-    }
-    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 zipEncodeLength(unsigned char *p, unsigned char encoding, unsigned int rawlen) {
 /* 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 zipEncodeLength(unsigned char *p, unsigned char encoding, unsigned int rawlen) {


@@ -199,17 +189,33 @@ static unsigned int zipEncodeLength(unsigned char *p, unsigned char encoding, un
     return len;
 }
 
     return len;
 }
 

-/* Decode the length of the previous element stored at "p". */
-static unsigned int zipPrevDecodeLength(unsigned char *p, unsigned int *lensize) {
-    unsigned int len = *p;
-    if (len < ZIP_BIGLEN) {
-        if (lensize) *lensize = 1;
-    } else {
-        if (lensize) *lensize = 1+sizeof(len);
-        memcpy(&len,p+1,sizeof(len));
-    }
-    return len;
-}
+/* Decode the length encoded in 'ptr'. The 'encoding' variable will hold the
+ * entries encoding, the 'lensize' variable will hold the number of bytes
+ * required to encode the entries length, and the 'len' variable will hold the
+ * entries length. */
+#define ZIP_DECODE_LENGTH(ptr, encoding, lensize, len) do {                    \
+    ZIP_ENTRY_ENCODING((ptr), (encoding));                                     \
+    if ((encoding) < ZIP_STR_MASK) {                                           \
+        if ((encoding) == ZIP_STR_06B) {                                       \
+            (lensize) = 1;                                                     \
+            (len) = (ptr)[0] & 0x3f;                                           \
+        } else if ((encoding) == ZIP_STR_14B) {                                \
+            (lensize) = 2;                                                     \
+            (len) = (((ptr)[0] & 0x3f) << 8) | (ptr)[1];                       \
+        } else if (encoding == ZIP_STR_32B) {                                  \
+            (lensize) = 5;                                                     \
+            (len) = ((ptr)[1] << 24) |                                         \
+                    ((ptr)[2] << 16) |                                         \
+                    ((ptr)[3] <<  8) |                                         \
+                    ((ptr)[4]);                                                \
+        } else {                                                               \
+            assert(NULL);                                                      \
+        }                                                                      \
+    } else {                                                                   \
+        (lensize) = 1;                                                         \
+        (len) = zipIntSize(encoding);                                          \
+    }                                                                          \
+} while(0);

 
 /* Encode the length of the previous entry and write it to "p". Return the
  * number of bytes needed to encode this length if "p" is NULL. */
 
 /* Encode the length of the previous entry and write it to "p". Return the
  * number of bytes needed to encode this length if "p" is NULL. */


@@ -223,6 +229,7 @@ static unsigned int zipPrevEncodeLength(unsigned char *p, unsigned int len) {
         } else {
             p[0] = ZIP_BIGLEN;
             memcpy(p+1,&len,sizeof(len));
         } else {
             p[0] = ZIP_BIGLEN;
             memcpy(p+1,&len,sizeof(len));

+            memrev32ifbe(p+1);

             return 1+sizeof(len);
         }
     }
             return 1+sizeof(len);
         }
     }


@@ -234,40 +241,65 @@ static void zipPrevEncodeLengthForceLarge(unsigned char *p, unsigned int len) {
     if (p == NULL) return;
     p[0] = ZIP_BIGLEN;
     memcpy(p+1,&len,sizeof(len));
     if (p == NULL) return;
     p[0] = ZIP_BIGLEN;
     memcpy(p+1,&len,sizeof(len));

+    memrev32ifbe(p+1);

 }
 
 }
 

-/* Return the difference in number of bytes needed to store the new length
- * "len" on the entry pointed to by "p". */
+/* Decode the number of bytes required to store the length of the previous
+ * element, from the perspective of the entry pointed to by 'ptr'. */
+#define ZIP_DECODE_PREVLENSIZE(ptr, prevlensize) do {                          \
+    if ((ptr)[0] < ZIP_BIGLEN) {                                               \
+        (prevlensize) = 1;                                                     \
+    } else {                                                                   \
+        (prevlensize) = 5;                                                     \
+    }                                                                          \
+} while(0);
+
+/* Decode the length of the previous element, from the perspective of the entry
+ * pointed to by 'ptr'. */
+#define ZIP_DECODE_PREVLEN(ptr, prevlensize, prevlen) do {                     \
+    ZIP_DECODE_PREVLENSIZE(ptr, prevlensize);                                  \
+    if ((prevlensize) == 1) {                                                  \
+        (prevlen) = (ptr)[0];                                                  \
+    } else if ((prevlensize) == 5) {                                           \
+        assert(sizeof((prevlensize)) == 4);                                    \
+        memcpy(&(prevlen), ((char*)(ptr)) + 1, 4);                             \
+        memrev32ifbe(&prevlen);                                                \
+    }                                                                          \
+} while(0);
+
+/* Return the difference in number of bytes needed to store the length of the
+ * previous element 'len', in the entry pointed to by 'p'. */

 static int zipPrevLenByteDiff(unsigned char *p, unsigned int len) {
     unsigned int prevlensize;
 static int zipPrevLenByteDiff(unsigned char *p, unsigned int len) {
     unsigned int prevlensize;

-    zipPrevDecodeLength(p,&prevlensize);
-    return zipPrevEncodeLength(NULL,len)-prevlensize;
+    ZIP_DECODE_PREVLENSIZE(p, prevlensize);
+    return zipPrevEncodeLength(NULL, len) - prevlensize;
+}
+
+/* Return the total number of bytes used by the entry pointed to by 'p'. */
+static unsigned int zipRawEntryLength(unsigned char *p) {
+    unsigned int prevlensize, encoding, lensize, len;
+    ZIP_DECODE_PREVLENSIZE(p, prevlensize);
+    ZIP_DECODE_LENGTH(p + prevlensize, encoding, lensize, len);
+    return prevlensize + lensize + len;

 }
 
 /* Check if string pointed to by 'entry' can be encoded as an integer.
  * Stores the integer value in 'v' and its encoding in 'encoding'. */
 static int zipTryEncoding(unsigned char *entry, unsigned int entrylen, long long *v, unsigned char *encoding) {
     long long value;
 }
 
 /* Check if string pointed to by 'entry' can be encoded as an integer.
  * Stores the integer value in 'v' and its encoding in 'encoding'. */
 static int zipTryEncoding(unsigned char *entry, unsigned int entrylen, long long *v, unsigned char *encoding) {
     long long value;

-    char *eptr;
-    char buf[32];

 
     if (entrylen >= 32 || entrylen == 0) return 0;
 
     if (entrylen >= 32 || entrylen == 0) return 0;

-    if (entry[0] == '-' || (entry[0] >= '0' && entry[0] <= '9')) {
-        int slen;
-
-        /* Perform a back-and-forth conversion to make sure that
-         * the string turned into an integer is not losing any info. */
-        memcpy(buf,entry,entrylen);
-        buf[entrylen] = '\0';
-        value = strtoll(buf,&eptr,10);
-        if (eptr[0] != '\0') return 0;
-        slen = ll2string(buf,32,value);
-        if (entrylen != (unsigned)slen || memcmp(buf,entry,slen)) return 0;
-
+    if (string2ll((char*)entry,entrylen,&value)) {

         /* Great, the string can be encoded. Check what's the smallest
          * of our encoding types that can hold this value. */
         /* Great, the string can be encoded. Check what's the smallest
          * of our encoding types that can hold this value. */

-        if (value >= INT16_MIN && value <= INT16_MAX) {
+        if (value >= 0 && value <= 12) {
+            *encoding = ZIP_INT_IMM_MIN+value;
+        } else if (value >= INT8_MIN && value <= INT8_MAX) {
+            *encoding = ZIP_INT_8B;
+        } else if (value >= INT16_MIN && value <= INT16_MAX) {

             *encoding = ZIP_INT_16B;
             *encoding = ZIP_INT_16B;

+        } else if (value >= INT24_MIN && value <= INT24_MAX) {
+            *encoding = ZIP_INT_24B;

         } else if (value >= INT32_MIN && value <= INT32_MAX) {
             *encoding = ZIP_INT_32B;
         } else {
         } else if (value >= INT32_MIN && value <= INT32_MAX) {
             *encoding = ZIP_INT_32B;
         } else {


@@ -284,15 +316,26 @@ static void zipSaveInteger(unsigned char *p, int64_t value, unsigned char encodi
     int16_t i16;
     int32_t i32;
     int64_t i64;
     int16_t i16;
     int32_t i32;
     int64_t i64;

-    if (encoding == ZIP_INT_16B) {
+    if (encoding == ZIP_INT_8B) {
+        ((int8_t*)p)[0] = (int8_t)value;
+    } else if (encoding == ZIP_INT_16B) {

         i16 = value;
         memcpy(p,&i16,sizeof(i16));
         i16 = value;
         memcpy(p,&i16,sizeof(i16));

+        memrev16ifbe(p);
+    } else if (encoding == ZIP_INT_24B) {
+        i32 = value<<8;
+        memrev32ifbe(&i32);
+        memcpy(p,((uint8_t*)&i32)+1,sizeof(i32)-sizeof(uint8_t));

     } else if (encoding == ZIP_INT_32B) {
         i32 = value;
         memcpy(p,&i32,sizeof(i32));
     } else if (encoding == ZIP_INT_32B) {
         i32 = value;
         memcpy(p,&i32,sizeof(i32));

+        memrev32ifbe(p);

     } else if (encoding == ZIP_INT_64B) {
         i64 = value;
         memcpy(p,&i64,sizeof(i64));
     } else if (encoding == ZIP_INT_64B) {
         i64 = value;
         memcpy(p,&i64,sizeof(i64));

+        memrev64ifbe(p);
+    } else if (encoding >= ZIP_INT_IMM_MIN && encoding <= ZIP_INT_IMM_MAX) {
+        /* Nothing to do, the value is stored in the encoding itself. */

     } else {
         assert(NULL);
     }
     } else {
         assert(NULL);
     }


@@ -303,15 +346,27 @@ static int64_t zipLoadInteger(unsigned char *p, unsigned char encoding) {
     int16_t i16;
     int32_t i32;
     int64_t i64, ret = 0;
     int16_t i16;
     int32_t i32;
     int64_t i64, ret = 0;

-    if (encoding == ZIP_INT_16B) {
+    if (encoding == ZIP_INT_8B) {
+        ret = ((int8_t*)p)[0];
+    } else if (encoding == ZIP_INT_16B) {

         memcpy(&i16,p,sizeof(i16));
         memcpy(&i16,p,sizeof(i16));

+        memrev16ifbe(&i16);

         ret = i16;
     } else if (encoding == ZIP_INT_32B) {
         memcpy(&i32,p,sizeof(i32));
         ret = i16;
     } else if (encoding == ZIP_INT_32B) {
         memcpy(&i32,p,sizeof(i32));

+        memrev32ifbe(&i32);

         ret = i32;
         ret = i32;

+    } else if (encoding == ZIP_INT_24B) {
+        i32 = 0;
+        memcpy(((uint8_t*)&i32)+1,p,sizeof(i32)-sizeof(uint8_t));
+        memrev32ifbe(&i32);
+        ret = i32>>8;

     } else if (encoding == ZIP_INT_64B) {
         memcpy(&i64,p,sizeof(i64));
     } else if (encoding == ZIP_INT_64B) {
         memcpy(&i64,p,sizeof(i64));

+        memrev64ifbe(&i64);

         ret = i64;
         ret = i64;

+    } else if (encoding >= ZIP_INT_IMM_MIN && encoding <= ZIP_INT_IMM_MAX) {
+        ret = (encoding & ZIP_INT_IMM_MASK)-1;

     } else {
         assert(NULL);
     }
     } else {
         assert(NULL);
     }


@@ -321,26 +376,20 @@ static int64_t zipLoadInteger(unsigned char *p, unsigned char encoding) {
 /* Return a struct with all information about an entry. */
 static zlentry zipEntry(unsigned char *p) {
     zlentry e;
 /* Return a struct with all information about an entry. */
 static zlentry zipEntry(unsigned char *p) {
     zlentry e;

-    e.prevrawlen = zipPrevDecodeLength(p,&e.prevrawlensize);
-    e.len = zipDecodeLength(p+e.prevrawlensize,&e.lensize);
-    e.headersize = e.prevrawlensize+e.lensize;
-    e.encoding = zipEntryEncoding(p+e.prevrawlensize);
+
+    ZIP_DECODE_PREVLEN(p, e.prevrawlensize, e.prevrawlen);
+    ZIP_DECODE_LENGTH(p + e.prevrawlensize, e.encoding, e.lensize, e.len);
+    e.headersize = e.prevrawlensize + e.lensize;

     e.p = p;
     return e;
 }
 
     e.p = p;
     return e;
 }
 

-/* Return the total number of bytes used by the entry at "p". */
-static unsigned int zipRawEntryLength(unsigned char *p) {
-    zlentry e = zipEntry(p);
-    return e.headersize + e.len;
-}
-

 /* Create a new empty ziplist. */
 unsigned char *ziplistNew(void) {
     unsigned int bytes = ZIPLIST_HEADER_SIZE+1;
     unsigned char *zl = zmalloc(bytes);
 /* Create a new empty ziplist. */
 unsigned char *ziplistNew(void) {
     unsigned int bytes = ZIPLIST_HEADER_SIZE+1;
     unsigned char *zl = zmalloc(bytes);

-    ZIPLIST_BYTES(zl) = bytes;
-    ZIPLIST_TAIL_OFFSET(zl) = ZIPLIST_HEADER_SIZE;
+    ZIPLIST_BYTES(zl) = intrev32ifbe(bytes);
+    ZIPLIST_TAIL_OFFSET(zl) = intrev32ifbe(ZIPLIST_HEADER_SIZE);

     ZIPLIST_LENGTH(zl) = 0;
     zl[bytes-1] = ZIP_END;
     return zl;
     ZIPLIST_LENGTH(zl) = 0;
     zl[bytes-1] = ZIP_END;
     return zl;


@@ -349,7 +398,7 @@ unsigned char *ziplistNew(void) {
 /* Resize the ziplist. */
 static unsigned char *ziplistResize(unsigned char *zl, unsigned int len) {
     zl = zrealloc(zl,len);
 /* Resize the ziplist. */
 static unsigned char *ziplistResize(unsigned char *zl, unsigned int len) {
     zl = zrealloc(zl,len);

-    ZIPLIST_BYTES(zl) = len;
+    ZIPLIST_BYTES(zl) = intrev32ifbe(len);

     zl[len-1] = ZIP_END;
     return zl;
 }
     zl[len-1] = ZIP_END;
     return zl;
 }


@@ -375,7 +424,7 @@ static unsigned char *ziplistResize(unsigned char *zl, unsigned int len) {
  * The pointer "p" points to the first entry that does NOT need to be
  * updated, i.e. consecutive fields MAY need an update. */
 static unsigned char *__ziplistCascadeUpdate(unsigned char *zl, unsigned char *p) {
  * The pointer "p" points to the first entry that does NOT need to be
  * updated, i.e. consecutive fields MAY need an update. */
 static unsigned char *__ziplistCascadeUpdate(unsigned char *zl, unsigned char *p) {

-    size_t curlen = ZIPLIST_BYTES(zl), rawlen, rawlensize;
+    size_t curlen = intrev32ifbe(ZIPLIST_BYTES(zl)), rawlen, rawlensize;

     size_t offset, noffset, extra;
     unsigned char *np;
     zlentry cur, next;
     size_t offset, noffset, extra;
     unsigned char *np;
     zlentry cur, next;


@@ -398,12 +447,19 @@ static unsigned char *__ziplistCascadeUpdate(unsigned char *zl, unsigned char *p
             offset = p-zl;
             extra = rawlensize-next.prevrawlensize;
             zl = ziplistResize(zl,curlen+extra);
             offset = p-zl;
             extra = rawlensize-next.prevrawlensize;
             zl = ziplistResize(zl,curlen+extra);

-            ZIPLIST_TAIL_OFFSET(zl) += extra;

             p = zl+offset;
 
             p = zl+offset;
 

-            /* Move the tail to the back. */
+            /* Current pointer and offset for next element. */

             np = p+rawlen;
             noffset = np-zl;
             np = p+rawlen;
             noffset = np-zl;

+
+            /* Update tail offset when next element is not the tail element. */
+            if ((zl+intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))) != np) {
+                ZIPLIST_TAIL_OFFSET(zl) =
+                    intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+extra);
+            }
+
+            /* Move the tail to the back. */

             memmove(np+rawlensize,
                 np+next.prevrawlensize,
                 curlen-noffset-next.prevrawlensize-1);
             memmove(np+rawlensize,
                 np+next.prevrawlensize,
                 curlen-noffset-next.prevrawlensize-1);


@@ -444,33 +500,39 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
     totlen = p-first.p;
     if (totlen > 0) {
         if (p[0] != ZIP_END) {
     totlen = p-first.p;
     if (totlen > 0) {
         if (p[0] != ZIP_END) {

-            /* Tricky: storing the prevlen in this entry might reduce or
-             * increase the number of bytes needed, compared to the current
-             * prevlen. Note that we can always store this length because
-             * it was previously stored by an entry that is being deleted. */
+            /* Storing `prevrawlen` in this entry may increase or decrease the
+             * number of bytes required compare to the current `prevrawlen`.
+             * There always is room to store this, because it was previously
+             * stored by an entry that is now being deleted. */

             nextdiff = zipPrevLenByteDiff(p,first.prevrawlen);
             nextdiff = zipPrevLenByteDiff(p,first.prevrawlen);

-            zipPrevEncodeLength(p-nextdiff,first.prevrawlen);
+            p -= nextdiff;
+            zipPrevEncodeLength(p,first.prevrawlen);

 
             /* Update offset for tail */
 
             /* Update offset for tail */

-            ZIPLIST_TAIL_OFFSET(zl) -= totlen;
+            ZIPLIST_TAIL_OFFSET(zl) =
+                intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))-totlen);

 
             /* When the tail contains more than one entry, we need to take
              * "nextdiff" in account as well. Otherwise, a change in the
              * size of prevlen doesn't have an effect on the *tail* offset. */
             tail = zipEntry(p);
 
             /* When the tail contains more than one entry, we need to take
              * "nextdiff" in account as well. Otherwise, a change in the
              * size of prevlen doesn't have an effect on the *tail* offset. */
             tail = zipEntry(p);

-            if (p[tail.headersize+tail.len] != ZIP_END)
-                ZIPLIST_TAIL_OFFSET(zl) += nextdiff;
+            if (p[tail.headersize+tail.len] != ZIP_END) {
+                ZIPLIST_TAIL_OFFSET(zl) =
+                   intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+nextdiff);
+            }

 
             /* Move tail to the front of the ziplist */
 
             /* Move tail to the front of the ziplist */

-            memmove(first.p,p-nextdiff,ZIPLIST_BYTES(zl)-(p-zl)-1+nextdiff);
+            memmove(first.p,p,
+                intrev32ifbe(ZIPLIST_BYTES(zl))-(p-zl)-1);

         } else {
             /* The entire tail was deleted. No need to move memory. */
         } else {
             /* The entire tail was deleted. No need to move memory. */

-            ZIPLIST_TAIL_OFFSET(zl) = (first.p-zl)-first.prevrawlen;
+            ZIPLIST_TAIL_OFFSET(zl) =
+                intrev32ifbe((first.p-zl)-first.prevrawlen);

         }
 
         /* Resize and update length */
         offset = first.p-zl;
         }
 
         /* Resize and update length */
         offset = first.p-zl;

-        zl = ziplistResize(zl, ZIPLIST_BYTES(zl)-totlen+nextdiff);
+        zl = ziplistResize(zl, intrev32ifbe(ZIPLIST_BYTES(zl))-totlen+nextdiff);

         ZIPLIST_INCR_LENGTH(zl,-deleted);
         p = zl+offset;
 
         ZIPLIST_INCR_LENGTH(zl,-deleted);
         p = zl+offset;
 


@@ -484,11 +546,13 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
 
 /* Insert item at "p". */
 static unsigned char *__ziplistInsert(unsigned char *zl, unsigned char *p, unsigned char *s, unsigned int slen) {
 
 /* Insert item at "p". */
 static unsigned char *__ziplistInsert(unsigned char *zl, unsigned char *p, unsigned char *s, unsigned int slen) {

-    size_t curlen = ZIPLIST_BYTES(zl), reqlen, prevlen = 0;
+    size_t curlen = intrev32ifbe(ZIPLIST_BYTES(zl)), reqlen, prevlen = 0;

     size_t offset;
     int nextdiff = 0;
     unsigned char encoding = 0;
     size_t offset;
     int nextdiff = 0;
     unsigned char encoding = 0;

-    long long value;
+    long long value = 123456789; /* initialized to avoid warning. Using a value
+                                    that is easy to see if for some reason
+                                    we use it uninitialized. */

     zlentry entry, tail;
 
     /* Find out prevlen for the entry that is inserted. */
     zlentry entry, tail;
 
     /* Find out prevlen for the entry that is inserted. */


@@ -535,17 +599,20 @@ static unsigned char *__ziplistInsert(unsigned char *zl, unsigned char *p, unsig
         zipPrevEncodeLength(p+reqlen,reqlen);
 
         /* Update offset for tail */
         zipPrevEncodeLength(p+reqlen,reqlen);
 
         /* Update offset for tail */

-        ZIPLIST_TAIL_OFFSET(zl) += reqlen;
+        ZIPLIST_TAIL_OFFSET(zl) =
+            intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+reqlen);

 
         /* When the tail contains more than one entry, we need to take
          * "nextdiff" in account as well. Otherwise, a change in the
          * size of prevlen doesn't have an effect on the *tail* offset. */
         tail = zipEntry(p+reqlen);
 
         /* When the tail contains more than one entry, we need to take
          * "nextdiff" in account as well. Otherwise, a change in the
          * size of prevlen doesn't have an effect on the *tail* offset. */
         tail = zipEntry(p+reqlen);

-        if (p[reqlen+tail.headersize+tail.len] != ZIP_END)
-            ZIPLIST_TAIL_OFFSET(zl) += nextdiff;
+        if (p[reqlen+tail.headersize+tail.len] != ZIP_END) {
+            ZIPLIST_TAIL_OFFSET(zl) =
+                intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+nextdiff);
+        }

     } else {
         /* This element will be the new tail. */
     } else {
         /* This element will be the new tail. */

-        ZIPLIST_TAIL_OFFSET(zl) = p-zl;
+        ZIPLIST_TAIL_OFFSET(zl) = intrev32ifbe(p-zl);

     }
 
     /* When nextdiff != 0, the raw length of the next entry has changed, so
     }
 
     /* When nextdiff != 0, the raw length of the next entry has changed, so


@@ -613,10 +680,14 @@ unsigned char *ziplistNext(unsigned char *zl, unsigned char *p) {
      * when the *next* element is ZIP_END (there is no next entry). */
     if (p[0] == ZIP_END) {
         return NULL;
      * when the *next* element is ZIP_END (there is no next entry). */
     if (p[0] == ZIP_END) {
         return NULL;

-    } else {
-        p = p+zipRawEntryLength(p);
-        return (p[0] == ZIP_END) ? NULL : p;

     }
     }

+
+    p += zipRawEntryLength(p);
+    if (p[0] == ZIP_END) {
+        return NULL;
+    }
+
+    return p;

 }
 
 /* Return pointer to previous entry in ziplist. */
 }
 
 /* Return pointer to previous entry in ziplist. */


@@ -703,22 +774,82 @@ unsigned int ziplistCompare(unsigned char *p, unsigned char *sstr, unsigned int
             return 0;
         }
     } else {
             return 0;
         }
     } else {

-        /* Try to compare encoded values */
+        /* Try to compare encoded values. Don't compare encoding because
+         * different implementations may encoded integers differently. */

         if (zipTryEncoding(sstr,slen,&sval,&sencoding)) {
         if (zipTryEncoding(sstr,slen,&sval,&sencoding)) {

-            if (entry.encoding == sencoding) {
-                zval = zipLoadInteger(p+entry.headersize,entry.encoding);
-                return zval == sval;
-            }
+          zval = zipLoadInteger(p+entry.headersize,entry.encoding);
+          return zval == sval;

         }
     }
     return 0;
 }
 
         }
     }
     return 0;
 }
 

+/* Find pointer to the entry equal to the specified entry. Skip 'skip' entries
+ * between every comparison. Returns NULL when the field could not be found. */
+unsigned char *ziplistFind(unsigned char *p, unsigned char *vstr, unsigned int vlen, unsigned int skip) {
+    int skipcnt = 0;
+    unsigned char vencoding = 0;
+    long long vll = 0;
+
+    while (p[0] != ZIP_END) {
+        unsigned int prevlensize, encoding, lensize, len;
+        unsigned char *q;
+
+        ZIP_DECODE_PREVLENSIZE(p, prevlensize);
+        ZIP_DECODE_LENGTH(p + prevlensize, encoding, lensize, len);
+        q = p + prevlensize + lensize;
+
+        if (skipcnt == 0) {
+            /* Compare current entry with specified entry */
+            if (ZIP_IS_STR(encoding)) {
+                if (len == vlen && memcmp(q, vstr, vlen) == 0) {
+                    return p;
+                }
+            } else {
+                /* Find out if the searched field can be encoded. Note that
+                 * we do it only the first time, once done vencoding is set
+                 * to non-zero and vll is set to the integer value. */
+                if (vencoding == 0) {
+                    if (!zipTryEncoding(vstr, vlen, &vll, &vencoding)) {
+                        /* If the entry can't be encoded we set it to
+                         * UCHAR_MAX so that we don't retry again the next
+                         * time. */
+                        vencoding = UCHAR_MAX;
+                    }
+                    /* Must be non-zero by now */
+                    assert(vencoding);
+                }
+
+                /* Compare current entry with specified entry, do it only
+                 * if vencoding != UCHAR_MAX because if there is no encoding
+                 * possible for the field it can't be a valid integer. */
+                if (vencoding != UCHAR_MAX) {
+                    long long ll = zipLoadInteger(q, encoding);
+                    if (ll == vll) {
+                        return p;
+                    }
+                }
+            }
+
+            /* Reset skip count */
+            skipcnt = skip;
+        } else {
+            /* Skip entry */
+            skipcnt--;
+        }
+
+        /* Move to next entry */
+        p = q + len;
+    }
+
+    return NULL;
+}
+

 /* Return length of ziplist. */
 unsigned int ziplistLen(unsigned char *zl) {
     unsigned int len = 0;
 /* Return length of ziplist. */
 unsigned int ziplistLen(unsigned char *zl) {
     unsigned int len = 0;

-    if (ZIPLIST_LENGTH(zl) < UINT16_MAX) {
-        len = ZIPLIST_LENGTH(zl);
+    if (intrev16ifbe(ZIPLIST_LENGTH(zl)) < UINT16_MAX) {
+        len = intrev16ifbe(ZIPLIST_LENGTH(zl));

     } else {
         unsigned char *p = zl+ZIPLIST_HEADER_SIZE;
         while (*p != ZIP_END) {
     } else {
         unsigned char *p = zl+ZIPLIST_HEADER_SIZE;
         while (*p != ZIP_END) {


@@ -727,14 +858,14 @@ unsigned int ziplistLen(unsigned char *zl) {
         }
 
         /* Re-store length if small enough */
         }
 
         /* Re-store length if small enough */

-        if (len < UINT16_MAX) ZIPLIST_LENGTH(zl) = len;
+        if (len < UINT16_MAX) ZIPLIST_LENGTH(zl) = intrev16ifbe(len);

     }
     return len;
 }
 
 /* Return ziplist blob size in bytes. */
 size_t ziplistBlobLen(unsigned char *zl) {
     }
     return len;
 }
 
 /* Return ziplist blob size in bytes. */
 size_t ziplistBlobLen(unsigned char *zl) {

-    return ZIPLIST_BYTES(zl);
+    return intrev32ifbe(ZIPLIST_BYTES(zl));

 }
 
 void ziplistRepr(unsigned char *zl) {
 }
 
 void ziplistRepr(unsigned char *zl) {


@@ -746,9 +877,9 @@ void ziplistRepr(unsigned char *zl) {
         "{total bytes %d} "
         "{length %u}\n"
         "{tail offset %u}\n",
         "{total bytes %d} "
         "{length %u}\n"
         "{tail offset %u}\n",

-        ZIPLIST_BYTES(zl),
-        ZIPLIST_LENGTH(zl),
-        ZIPLIST_TAIL_OFFSET(zl));
+        intrev32ifbe(ZIPLIST_BYTES(zl)),
+        intrev16ifbe(ZIPLIST_LENGTH(zl)),
+        intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl)));

     p = ZIPLIST_ENTRY_HEAD(zl);
     while(*p != ZIP_END) {
         entry = zipEntry(p);
     p = ZIPLIST_ENTRY_HEAD(zl);
     while(*p != ZIP_END) {
         entry = zipEntry(p);


@@ -849,7 +980,7 @@ void stress(int pos, int num, int maxsize, int dnum) {
             zl = ziplistDeleteRange(zl,0,1);
         }
         printf("List size: %8d, bytes: %8d, %dx push+pop (%s): %6lld usec\n",
             zl = ziplistDeleteRange(zl,0,1);
         }
         printf("List size: %8d, bytes: %8d, %dx push+pop (%s): %6lld usec\n",

-            i,ZIPLIST_BYTES(zl),num,posstr[pos],usec()-start);
+            i,intrev32ifbe(ZIPLIST_BYTES(zl)),num,posstr[pos],usec()-start);

         zfree(zl);
     }
 }
         zfree(zl);
     }
 }


@@ -879,7 +1010,7 @@ void pop(unsigned char *zl, int where) {
     }
 }
 
     }
 }
 

-void randstring(char *target, unsigned int min, unsigned int max) {
+int randstring(char *target, unsigned int min, unsigned int max) {

     int p, len = min+rand()%(max-min+1);
     int minval, maxval;
     switch(rand() % 3) {
     int p, len = min+rand()%(max-min+1);
     int minval, maxval;
     switch(rand() % 3) {


@@ -901,9 +1032,24 @@ void randstring(char *target, unsigned int min, unsigned int max) {
 
     while(p < len)
         target[p++] = minval+rand()%(maxval-minval+1);
 
     while(p < len)
         target[p++] = minval+rand()%(maxval-minval+1);

-    return;
+    return len;

 }
 
 }
 

+void verify(unsigned char *zl, zlentry *e) {
+    int i;
+    int len = ziplistLen(zl);
+    zlentry _e;
+
+    for (i = 0; i < len; i++) {
+        memset(&e[i], 0, sizeof(zlentry));
+        e[i] = zipEntry(ziplistIndex(zl, i));
+
+        memset(&_e, 0, sizeof(zlentry));
+        _e = zipEntry(ziplistIndex(zl, -len+i));
+
+        assert(memcmp(&e[i], &_e, sizeof(zlentry)) == 0);
+    }
+}

 
 int main(int argc, char **argv) {
     unsigned char *zl, *p;
 
 int main(int argc, char **argv) {
     unsigned char *zl, *p;


@@ -1186,6 +1332,43 @@ int main(int argc, char **argv) {
         printf("SUCCESS\n\n");
     }
 
         printf("SUCCESS\n\n");
     }
 

+    printf("Regression test deleting next to last entries:\n");
+    {
+        char v[3][257];
+        zlentry e[3];
+        int i;
+
+        for (i = 0; i < (sizeof(v)/sizeof(v[0])); i++) {
+            memset(v[i], 'a' + i, sizeof(v[0]));
+        }
+
+        v[0][256] = '\0';
+        v[1][  1] = '\0';
+        v[2][256] = '\0';
+
+        zl = ziplistNew();
+        for (i = 0; i < (sizeof(v)/sizeof(v[0])); i++) {
+            zl = ziplistPush(zl, (unsigned char *) v[i], strlen(v[i]), ZIPLIST_TAIL);
+        }
+
+        verify(zl, e);
+
+        assert(e[0].prevrawlensize == 1);
+        assert(e[1].prevrawlensize == 5);
+        assert(e[2].prevrawlensize == 1);
+
+        /* Deleting entry 1 will increase `prevrawlensize` for entry 2 */
+        unsigned char *p = e[1].p;
+        zl = ziplistDelete(zl, &p);
+
+        verify(zl, e);
+
+        assert(e[0].prevrawlensize == 1);
+        assert(e[1].prevrawlensize == 5);
+
+        printf("SUCCESS\n\n");
+    }
+

     printf("Create long list and check indices:\n");
     {
         zl = ziplistNew();
     printf("Create long list and check indices:\n");
     {
         zl = ziplistNew();


@@ -1237,6 +1420,7 @@ int main(int argc, char **argv) {
         int i,j,len,where;
         unsigned char *p;
         char buf[1024];
         int i,j,len,where;
         unsigned char *p;
         char buf[1024];

+        int buflen;

         list *ref;
         listNode *refnode;
 
         list *ref;
         listNode *refnode;
 


@@ -1245,10 +1429,6 @@ int main(int argc, char **argv) {
         unsigned int slen;
         long long sval;
 
         unsigned int slen;
         long long sval;
 

-        /* In the regression for the cascade bug, it was triggered
-         * with a random seed of 2. */
-        srand(2);
-

         for (i = 0; i < 20000; i++) {
             zl = ziplistNew();
             ref = listCreate();
         for (i = 0; i < 20000; i++) {
             zl = ziplistNew();
             ref = listCreate();


@@ -1258,31 +1438,32 @@ int main(int argc, char **argv) {
             /* Create lists */
             for (j = 0; j < len; j++) {
                 where = (rand() & 1) ? ZIPLIST_HEAD : ZIPLIST_TAIL;
             /* Create lists */
             for (j = 0; j < len; j++) {
                 where = (rand() & 1) ? ZIPLIST_HEAD : ZIPLIST_TAIL;

-                switch(rand() % 4) {
-                case 0:
-                    sprintf(buf,"%lld",(0LL + rand()) >> 20);
-                    break;
-                case 1:
-                    sprintf(buf,"%lld",(0LL + rand()));
-                    break;
-                case 2:
-                    sprintf(buf,"%lld",(0LL + rand()) << 20);
-                    break;
-                case 3:
-                    randstring(buf,0,256);
-                break;
-                default:
-                    assert(NULL);
+                if (rand() % 2) {
+                    buflen = randstring(buf,1,sizeof(buf)-1);
+                } else {
+                    switch(rand() % 3) {
+                    case 0:
+                        buflen = sprintf(buf,"%lld",(0LL + rand()) >> 20);
+                        break;
+                    case 1:
+                        buflen = sprintf(buf,"%lld",(0LL + rand()));
+                        break;
+                    case 2:
+                        buflen = sprintf(buf,"%lld",(0LL + rand()) << 20);
+                        break;
+                    default:
+                        assert(NULL);
+                    }

                 }
 
                 /* Add to ziplist */
                 }
 
                 /* Add to ziplist */

-                zl = ziplistPush(zl, (unsigned char*)buf, strlen(buf), where);
+                zl = ziplistPush(zl, (unsigned char*)buf, buflen, where);

 
                 /* Add to reference list */
                 if (where == ZIPLIST_HEAD) {
 
                 /* Add to reference list */
                 if (where == ZIPLIST_HEAD) {

-                    listAddNodeHead(ref,sdsnew(buf));
+                    listAddNodeHead(ref,sdsnewlen(buf, buflen));

                 } else if (where == ZIPLIST_TAIL) {
                 } else if (where == ZIPLIST_TAIL) {

-                    listAddNodeTail(ref,sdsnew(buf));
+                    listAddNodeTail(ref,sdsnewlen(buf, buflen));

                 } else {
                     assert(NULL);
                 }
                 } else {
                     assert(NULL);
                 }


@@ -1297,12 +1478,13 @@ int main(int argc, char **argv) {
 
                 assert(ziplistGet(p,&sstr,&slen,&sval));
                 if (sstr == NULL) {
 
                 assert(ziplistGet(p,&sstr,&slen,&sval));
                 if (sstr == NULL) {

-                    sprintf(buf,"%lld",sval);
+                    buflen = sprintf(buf,"%lld",sval);

                 } else {
                 } else {

-                    memcpy(buf,sstr,slen);
-                    buf[slen] = '\0';
+                    buflen = slen;
+                    memcpy(buf,sstr,buflen);
+                    buf[buflen] = '\0';

                 }
                 }

-                assert(strcmp(buf,listNodeValue(refnode)) == 0);
+                assert(memcmp(buf,listNodeValue(refnode),buflen) == 0);

             }
             zfree(zl);
             listRelease(ref);
             }
             zfree(zl);
             listRelease(ref);