C++ ziplistGet函数代码示例

void lindexCommand(redisClient *c) {
    robj *o = lookupKeyReadOrReply(c,c->argv[1],shared.nullbulk);
    if (o == NULL || checkType(c,o,REDIS_LIST)) return;
    int index = atoi(c->argv[2]->ptr);
    robj *value = NULL;

    if (o->encoding == REDIS_ENCODING_ZIPLIST) {
        unsigned char *p;
        unsigned char *vstr;
        unsigned int vlen;
        long long vlong;
        p = ziplistIndex(o->ptr,index);
        if (ziplistGet(p,&vstr,&vlen,&vlong)) {
            if (vstr) {
                value = createStringObject((char*)vstr,vlen);
            } else {
                value = createStringObjectFromLongLong(vlong);
            }
            addReplyBulk(c,value);
            decrRefCount(value);
        } else {
            addReply(c,shared.nullbulk);
        }
    } else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
        listNode *ln = listIndex(o->ptr,index);
        if (ln != NULL) {
            value = listNodeValue(ln);
            addReplyBulk(c,value);
        } else {
            addReply(c,shared.nullbulk);
        }
    } else {
        redisPanic("Unknown list encoding");
    }
}

/* Get the value from a ziplist encoded hash, identified by field.
 * Returns -1 when the field cannot be found. */
int hashTypeGetFromZiplist(robj *o, robj *field,
                           unsigned char **vstr,
                           unsigned int *vlen,
                           long long *vll)
{
    unsigned char *zl, *fptr = NULL, *vptr = NULL;
    int ret;

    logicErrorExpr(o->encoding == REDIS_ENCODING_ZIPLIST, "Never happend");

    field = getDecodedObject(field);

    zl = o->ptr;
    fptr = ziplistIndex(zl, ZIPLIST_HEAD);
    if (fptr != NULL) {
        fptr = ziplistFind(fptr, field->ptr, sdslen(field->ptr), 1);
        if (fptr != NULL) {
            /* Grab pointer to the value (fptr points to the field) */
            vptr = ziplistNext(zl, fptr);
            logicErrorExpr(vptr != NULL, "Never happend");
        }
    }

    decrRefCount(field);

    if (vptr != NULL) {
        ret = ziplistGet(vptr, vstr, vlen, vll);
        logicErrorExpr(ret, "Never happend");
        return 0;
    }

    return -1;
}

/* Get the field or value at iterator cursor, for an iterator on a hash value
 * encoded as a ziplist. Prototype is similar to `hashTypeGetFromZiplist`. */
void hashTypeCurrentFromZiplist(hashTypeIterator *hi, int what,
                                unsigned char **vstr,
                                unsigned int *vlen,
                                long long *vll)
{
    int ret;

    logicErrorExpr(hi->encoding == REDIS_ENCODING_ZIPLIST, "Invalid type");

    if (what & REDIS_HASH_KEY) {
        ret = ziplistGet(hi->fptr, vstr, vlen, vll);
        logicErrorExpr(ret, "Never happend");
    } else {
            ret = ziplistGet(hi->vptr, vstr, vlen, vll);
            logicErrorExpr(ret, "Never happend");
    }
}

void lrangeCommand(redisClient *c) {
    robj *o;
    long start, end, llen, rangelen;

    if ((getLongFromObjectOrReply(c, c->argv[2], &start, NULL) != REDIS_OK) ||
        (getLongFromObjectOrReply(c, c->argv[3], &end, NULL) != REDIS_OK)) return;

    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.emptymultibulk)) == NULL
         || checkType(c,o,REDIS_LIST)) return;
    llen = listTypeLength(o);

    /* convert negative indexes */
    if (start < 0) start = llen+start;
    if (end < 0) end = llen+end;
    if (start < 0) start = 0;

    /* Invariant: start >= 0, so this test will be true when end < 0.
     * The range is empty when start > end or start >= length. */
    if (start > end || start >= llen) {
        addReply(c,shared.emptymultibulk);
        return;
    }
    if (end >= llen) end = llen-1;
    rangelen = (end-start)+1;

    /* Return the result in form of a multi-bulk reply */
    addReplyMultiBulkLen(c,rangelen);
    if (o->encoding == REDIS_ENCODING_ZIPLIST) {
        unsigned char *p = ziplistIndex(o->ptr,start);
        unsigned char *vstr;
        unsigned int vlen;
        long long vlong;

        while(rangelen--) {
            ziplistGet(p,&vstr,&vlen,&vlong);
            if (vstr) {
                addReplyBulkCBuffer(c,vstr,vlen);
            } else {
                addReplyBulkLongLong(c,vlong);
            }
            p = ziplistNext(o->ptr,p);
        }
    } else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
        listNode *ln;

        /* If we are nearest to the end of the list, reach the element
         * starting from tail and going backward, as it is faster. */
        if (start > llen/2) start -= llen;
        ln = listIndex(o->ptr,start);

        while(rangelen--) {
            addReplyBulk(c,ln->value);
            ln = ln->next;
        }
    } else {
        redisPanic("List encoding is not LINKEDLIST nor ZIPLIST!");
    }
}

void pop(unsigned char *zl, int where) {
    unsigned char *p, *vstr;
    unsigned int vlen;
    long long vlong;

    p = ziplistIndex(zl,where == ZIPLIST_HEAD ? 0 : -1);
    if (ziplistGet(p,&vstr,&vlen,&vlong)) {
        if (where == ZIPLIST_HEAD)
            printf("Pop head: ");
        else
            printf("Pop tail: ");

        if (vstr)
            if (vlen && fwrite(vstr,vlen,1,stdout) == 0) perror("fwrite");
        else
            printf("%lld", vlong);

        printf("\n");
        ziplistDeleteRange(zl,-1,1);
    } else {
        printf("ERROR: Could not pop\n");
        exit(1);
    }
}

robj *listTypePop(robj *subject, int where) {
    robj *value = NULL;
    if (subject->encoding == REDIS_ENCODING_ZIPLIST) {
        unsigned char *p;
        unsigned char *vstr;
        unsigned int vlen;
        long long vlong;
        int pos = (where == REDIS_HEAD) ? 0 : -1;
        p = ziplistIndex(subject->ptr,pos);
        if (ziplistGet(p,&vstr,&vlen,&vlong)) {
            if (vstr) {
                value = createStringObject((char*)vstr,vlen);
            } else {
                value = createStringObjectFromLongLong(vlong);
            }
            /* We only need to delete an element when it exists */
            subject->ptr = ziplistDelete(subject->ptr,&p);
        }
    } else if (subject->encoding == REDIS_ENCODING_LINKEDLIST) {
        list *list = subject->ptr;
        listNode *ln;
        if (where == REDIS_HEAD) {
            ln = listFirst(list);
        } else {
            ln = listLast(list);
        }
        if (ln != NULL) {
            value = listNodeValue(ln);
            incrRefCount(value);
            listDelNode(list,ln);
        }
    } else {
        redisPanic("Unknown list encoding");
    }
    return value;
}

/* Return entry or NULL at the current position of the iterator. */
robj *listTypeGet(listTypeEntry *entry) {
    listTypeIterator *li = entry->li;
    robj *value = NULL;
    if (li->encoding == REDIS_ENCODING_ZIPLIST) {
        unsigned char *vstr;
        unsigned int vlen;
        long long vlong;
        redisAssert(entry->zi != NULL);
        if (ziplistGet(entry->zi,&vstr,&vlen,&vlong)) {
            if (vstr) {
                value = createStringObject((char*)vstr,vlen);
            } else {
                value = createStringObjectFromLongLong(vlong);
            }
        }
    } else if (li->encoding == REDIS_ENCODING_LINKEDLIST) {
        redisAssert(entry->ln != NULL);
        value = listNodeValue(entry->ln);
        incrRefCount(value);
    } else {
        redisPanic("Unknown list encoding");
    }
    return value;
}

static void *loadZsetZiplistObject(unsigned char* zl, unsigned int *rlen) {
    unsigned int i = 0, len;
    unsigned char *eptr, *sptr;
    unsigned char *vstr;
    unsigned int vlen;
    int buf_len;
    long long vlong;
    double score;
    char buf[128];
    sds ele;

    len = ziplistLen (zl);
    eptr = ziplistIndex(zl,0);
    sptr = ziplistNext(zl,eptr);
    if(rdb_version < 2) {
        *rlen = len * 2;
    } else {
        *rlen = len;
    }
    sds *results = zmalloc(*rlen * sizeof(sds));
    while (eptr != NULL) {
        score = zzlGetScore(sptr);
        ziplistGet(eptr,&vstr,&vlen,&vlong);
        if (vstr == NULL)
            ele = sdsfromlonglong(vlong);
        else
            ele = sdsnewlen((char*)vstr,vlen);
        results[i] = ele;
        buf_len = snprintf(buf, 128, "%f", score);
        results[i+1] = sdsnewlen(buf, buf_len);
        i += 2;
        zzlNext(zl,&eptr,&sptr);
    }

    return results;
}

int 
main(int argc, char *argv[])
{
    unsigned char *zl, *p;
    unsigned char *entry;
    unsigned int elen;
    long long value;

    /* If an argument is given, use it as the random seed. */
    if (argc == 2)
        srand(atoi(argv[1]));

    zl = createIntList();
    ziplistRepr(zl);

    zl = createList();
    ziplistRepr(zl);

    pop(zl,ZIPLIST_TAIL);
    ziplistRepr(zl);

    pop(zl,ZIPLIST_HEAD);
    ziplistRepr(zl);

    pop(zl,ZIPLIST_TAIL);
    ziplistRepr(zl);

    pop(zl,ZIPLIST_TAIL);
    ziplistRepr(zl);

    printf("Get element at index 3:\n");
    {
        zl = createList();
        p = ziplistIndex(zl, 3);
        if (!ziplistGet(p, &entry, &elen, &value)) {
            printf("ERROR: Could not access index 3\n");
            return 1;
        }
        if (entry) {
            if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");
            printf("\n");
        } else {
            printf("%lld\n", value);
        }
        printf("\n");
    }

    printf("Get element at index 4 (out of range):\n");
    {
        zl = createList();
        p = ziplistIndex(zl, 4);
        if (p == NULL) {
            printf("No entry\n");
        } else {
            printf("ERROR: Out of range index should return NULL, returned offset: %ld\n", p-zl);
            return 1;
        }
        printf("\n");
    }

    printf("Get element at index -1 (last element):\n");
    {
        zl = createList();
        p = ziplistIndex(zl, -1);
        if (!ziplistGet(p, &entry, &elen, &value)) {
            printf("ERROR: Could not access index -1\n");
            return 1;
        }
        if (entry) {
            if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");
            printf("\n");
        } else {
            printf("%lld\n", value);
        }
        printf("\n");
    }

    printf("Get element at index -4 (first element):\n");
    {
        zl = createList();
        p = ziplistIndex(zl, -4);
        if (!ziplistGet(p, &entry, &elen, &value)) {
            printf("ERROR: Could not access index -4\n");
            return 1;
        }
        if (entry) {
            if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");
            printf("\n");
        } else {
            printf("%lld\n", value);
        }
        printf("\n");
    }

    printf("Get element at index -5 (reverse out of range):\n");
    {
        zl = createList();
        p = ziplistIndex(zl, -5);
        if (p == NULL) {
            printf("No entry\n");
//.........这里部分代码省略.........

//.........这里部分代码省略.........

    if (ht) {
        void *privdata[2];
        /* We set the max number of iterations to ten times the specified
         * COUNT, so if the hash table is in a pathological state (very
         * sparsely populated) we avoid to block too much time at the cost
         * of returning no or very few elements. */
        long maxiterations = count*10;

        /* We pass two pointers to the callback: the list to which it will
         * add new elements, and the object containing the dictionary so that
         * it is possible to fetch more data in a type-dependent way. */
        privdata[0] = keys;
        privdata[1] = o;
        do {
            cursor = dictScan(ht, cursor, scanCallback, privdata);
        } while (cursor &&
              maxiterations-- &&
              listLength(keys) < (unsigned long)count);
    } else if (o->type == OBJ_SET) {
        int pos = 0;
        int64_t ll;

        while(intsetGet(o->ptr,pos++,&ll))
            listAddNodeTail(keys,createStringObjectFromLongLong(ll));
        cursor = 0;
    } else if (o->type == OBJ_HASH || o->type == OBJ_ZSET) {
        unsigned char *p = ziplistIndex(o->ptr,0);
        unsigned char *vstr;
        unsigned int vlen;
        long long vll;

        while(p) {
            ziplistGet(p,&vstr,&vlen,&vll);
            listAddNodeTail(keys,
                (vstr != NULL) ? createStringObject((char*)vstr,vlen) :
                                 createStringObjectFromLongLong(vll));
            p = ziplistNext(o->ptr,p);
        }
        cursor = 0;
    } else {
        serverPanic("Not handled encoding in SCAN.");
    }

    /* Step 3: Filter elements. */
    node = listFirst(keys);
    while (node) {
        robj *kobj = listNodeValue(node);
        nextnode = listNextNode(node);
        int filter = 0;

        /* Filter element if it does not match the pattern. */
        if (!filter && use_pattern) {
            if (sdsEncodedObject(kobj)) {
                if (!stringmatchlen(pat, patlen, kobj->ptr, sdslen(kobj->ptr), 0))
                    filter = 1;
            } else {
                char buf[LONG_STR_SIZE];
                int len;

                serverAssert(kobj->encoding == OBJ_ENCODING_INT);
                len = ll2string(buf,sizeof(buf),(long)kobj->ptr);
                if (!stringmatchlen(pat, patlen, buf, len, 0)) filter = 1;
            }
        }

/* Write a sequence of commands able to fully rebuild the dataset into
 * "filename". Used both by REWRITEAOF and BGREWRITEAOF. */
int rewriteAppendOnlyFile(char *filename) {
    dictIterator *di = NULL;
    dictEntry *de;
    FILE *fp;
    char tmpfile[256];
    int j;
    time_t now = time(NULL);

    /* Note that we have to use a different temp name here compared to the
     * one used by rewriteAppendOnlyFileBackground() function. */
    snprintf(tmpfile,256,"temp-rewriteaof-%d.aof", (int) getpid());
    fp = fopen(tmpfile,"w");
    if (!fp) {
        redisLog(REDIS_WARNING, "Failed rewriting the append only file: %s", strerror(errno));
        return REDIS_ERR;
    }
    for (j = 0; j < server.dbnum; j++) {
        char selectcmd[] = "*2\r\n$6\r\nSELECT\r\n";
        redisDb *db = server.db+j;
        dict *d = db->dict;
        if (dictSize(d) == 0) continue;
        di = dictGetSafeIterator(d);
        if (!di) {
            fclose(fp);
            return REDIS_ERR;
        }

        /* SELECT the new DB */
        if (fwrite(selectcmd,sizeof(selectcmd)-1,1,fp) == 0) goto werr;
        if (fwriteBulkLongLong(fp,j) == 0) goto werr;

        /* Iterate this DB writing every entry */
        while((de = dictNext(di)) != NULL) {
            sds keystr = dictGetEntryKey(de);
            robj key, *o;
            time_t expiretime;
            int swapped;

            keystr = dictGetEntryKey(de);
            o = dictGetEntryVal(de);
            initStaticStringObject(key,keystr);
            /* If the value for this key is swapped, load a preview in memory.
             * We use a "swapped" flag to remember if we need to free the
             * value object instead to just increment the ref count anyway
             * in order to avoid copy-on-write of pages if we are forked() */
            if (!server.vm_enabled || o->storage == REDIS_VM_MEMORY ||
                o->storage == REDIS_VM_SWAPPING) {
                swapped = 0;
            } else {
                o = vmPreviewObject(o);
                swapped = 1;
            }
            expiretime = getExpire(db,&key);

            /* Save the key and associated value */
            if (o->type == REDIS_STRING) {
                /* Emit a SET command */
                char cmd[]="*3\r\n$3\r\nSET\r\n";
                if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
                /* Key and value */
                if (fwriteBulkObject(fp,&key) == 0) goto werr;
                if (fwriteBulkObject(fp,o) == 0) goto werr;
            } else if (o->type == REDIS_LIST) {
                /* Emit the RPUSHes needed to rebuild the list */
                char cmd[]="*3\r\n$5\r\nRPUSH\r\n";
                if (o->encoding == REDIS_ENCODING_ZIPLIST) {
                    unsigned char *zl = o->ptr;
                    unsigned char *p = ziplistIndex(zl,0);
                    unsigned char *vstr;
                    unsigned int vlen;
                    long long vlong;

                    while(ziplistGet(p,&vstr,&vlen,&vlong)) {
                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
                        if (vstr) {
                            if (fwriteBulkString(fp,(char*)vstr,vlen) == 0)
                                goto werr;
                        } else {
                            if (fwriteBulkLongLong(fp,vlong) == 0)
                                goto werr;
                        }
                        p = ziplistNext(zl,p);
                    }
                } else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
                    list *list = o->ptr;
                    listNode *ln;
                    listIter li;

                    listRewind(list,&li);
                    while((ln = listNext(&li))) {
                        robj *eleobj = listNodeValue(ln);

                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
                        if (fwriteBulkObject(fp,eleobj) == 0) goto werr;
                    }
                } else {
//.........这里部分代码省略.........