redis/src/modules/hellotype.c

/* This file implements a new module native data type called "HELLOTYPE".
 * The data structure implemented is a very simple ordered linked list of
 * 64 bit integers, in order to have something that is real world enough, but
 * at the same time, extremely simple to understand, to show how the API
 * works, how a new data type is created, and how to write basic methods
 * for RDB loading, saving and AOF rewriting.
 *
 * -----------------------------------------------------------------------------
 *
 * Copyright (c) 2016-Present, Redis Ltd.
 * All rights reserved.
 *
 * Licensed under your choice of (a) the Redis Source Available License 2.0
 * (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the
 * GNU Affero General Public License v3 (AGPLv3).
 */

#include "../redismodule.h"
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <stdint.h>

static RedisModuleType *HelloType;

/* ========================== Internal data structure  =======================
 * This is just a linked list of 64 bit integers where elements are inserted
 * in-place, so it's ordered. There is no pop/push operation but just insert
 * because it is enough to show the implementation of new data types without
 * making things complex. */

struct HelloTypeNode {
    int64_t value;
    struct HelloTypeNode *next;
};

struct HelloTypeObject {
    struct HelloTypeNode *head;
    size_t len; /* Number of elements added. */
};

struct HelloTypeObject *createHelloTypeObject(void) {
    struct HelloTypeObject *o;
    o = RedisModule_Alloc(sizeof(*o));
    o->head = NULL;
    o->len = 0;
    return o;
}

void HelloTypeInsert(struct HelloTypeObject *o, int64_t ele) {
    struct HelloTypeNode *next = o->head, *newnode, *prev = NULL;

    while(next && next->value < ele) {
        prev = next;
        next = next->next;
    }
    newnode = RedisModule_Alloc(sizeof(*newnode));
    newnode->value = ele;
    newnode->next = next;
    if (prev) {
        prev->next = newnode;
    } else {
        o->head = newnode;
    }
    o->len++;
}

void HelloTypeReleaseObject(struct HelloTypeObject *o) {
    struct HelloTypeNode *cur, *next;
    cur = o->head;
    while(cur) {
        next = cur->next;
        RedisModule_Free(cur);
        cur = next;
    }
    RedisModule_Free(o);
}

/* ========================= "hellotype" type commands ======================= */

/* HELLOTYPE.INSERT key value */
int HelloTypeInsert_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */

    if (argc != 3) return RedisModule_WrongArity(ctx);
    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
        REDISMODULE_READ|REDISMODULE_WRITE);
    int type = RedisModule_KeyType(key);
    if (type != REDISMODULE_KEYTYPE_EMPTY &&
        RedisModule_ModuleTypeGetType(key) != HelloType)
    {
        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
    }

    long long value;
    if ((RedisModule_StringToLongLong(argv[2],&value) != REDISMODULE_OK)) {
        return RedisModule_ReplyWithError(ctx,"ERR invalid value: must be a signed 64 bit integer");
    }

    /* Create an empty value object if the key is currently empty. */
    struct HelloTypeObject *hto;
    if (type == REDISMODULE_KEYTYPE_EMPTY) {
        hto = createHelloTypeObject();
        RedisModule_ModuleTypeSetValue(key,HelloType,hto);
    } else {
        hto = RedisModule_ModuleTypeGetValue(key);
    }

    /* Insert the new element. */
    HelloTypeInsert(hto,value);
    RedisModule_SignalKeyAsReady(ctx,argv[1]);

    RedisModule_ReplyWithLongLong(ctx,hto->len);
    RedisModule_ReplicateVerbatim(ctx);
    return REDISMODULE_OK;
}

/* HELLOTYPE.RANGE key first count */
int HelloTypeRange_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */

    if (argc != 4) return RedisModule_WrongArity(ctx);
    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
        REDISMODULE_READ|REDISMODULE_WRITE);
    int type = RedisModule_KeyType(key);
    if (type != REDISMODULE_KEYTYPE_EMPTY &&
        RedisModule_ModuleTypeGetType(key) != HelloType)
    {
        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
    }

    long long first, count;
    if (RedisModule_StringToLongLong(argv[2],&first) != REDISMODULE_OK ||
        RedisModule_StringToLongLong(argv[3],&count) != REDISMODULE_OK ||
        first < 0 || count < 0)
    {
        return RedisModule_ReplyWithError(ctx,
            "ERR invalid first or count parameters");
    }

    struct HelloTypeObject *hto = RedisModule_ModuleTypeGetValue(key);
    struct HelloTypeNode *node = hto ? hto->head : NULL;
    RedisModule_ReplyWithArray(ctx,REDISMODULE_POSTPONED_LEN);
    long long arraylen = 0;
    while(node && count--) {
        RedisModule_ReplyWithLongLong(ctx,node->value);
        arraylen++;
        node = node->next;
    }
    RedisModule_ReplySetArrayLength(ctx,arraylen);
    return REDISMODULE_OK;
}

/* HELLOTYPE.LEN key */
int HelloTypeLen_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */

    if (argc != 2) return RedisModule_WrongArity(ctx);
    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
        REDISMODULE_READ|REDISMODULE_WRITE);
    int type = RedisModule_KeyType(key);
    if (type != REDISMODULE_KEYTYPE_EMPTY &&
        RedisModule_ModuleTypeGetType(key) != HelloType)
    {
        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
    }

    struct HelloTypeObject *hto = RedisModule_ModuleTypeGetValue(key);
    RedisModule_ReplyWithLongLong(ctx,hto ? hto->len : 0);
    return REDISMODULE_OK;
}

/* ====================== Example of a blocking command ==================== */

/* Reply callback for blocking command HELLOTYPE.BRANGE, this will get
 * called when the key we blocked for is ready: we need to check if we
 * can really serve the client, and reply OK or ERR accordingly. */
int HelloBlock_Reply(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
    REDISMODULE_NOT_USED(argv);
    REDISMODULE_NOT_USED(argc);

    RedisModuleString *keyname = RedisModule_GetBlockedClientReadyKey(ctx);
    RedisModuleKey *key = RedisModule_OpenKey(ctx,keyname,REDISMODULE_READ);
    int type = RedisModule_KeyType(key);
    if (type != REDISMODULE_KEYTYPE_MODULE ||
        RedisModule_ModuleTypeGetType(key) != HelloType)
    {
        RedisModule_CloseKey(key);
        return REDISMODULE_ERR;
    }

    /* In case the key is able to serve our blocked client, let's directly
     * use our original command implementation to make this example simpler. */
    RedisModule_CloseKey(key);
    return HelloTypeRange_RedisCommand(ctx,argv,argc-1);
}

/* Timeout callback for blocking command HELLOTYPE.BRANGE */
int HelloBlock_Timeout(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
    REDISMODULE_NOT_USED(argv);
    REDISMODULE_NOT_USED(argc);
    return RedisModule_ReplyWithSimpleString(ctx,"Request timedout");
}

/* Private data freeing callback for HELLOTYPE.BRANGE command. */
void HelloBlock_FreeData(RedisModuleCtx *ctx, void *privdata) {
    REDISMODULE_NOT_USED(ctx);
    RedisModule_Free(privdata);
}

/* HELLOTYPE.BRANGE key first count timeout -- This is a blocking version of
 * the RANGE operation, in order to show how to use the API
 * RedisModule_BlockClientOnKeys(). */
int HelloTypeBRange_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
    if (argc != 5) return RedisModule_WrongArity(ctx);
    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
        REDISMODULE_READ|REDISMODULE_WRITE);
    int type = RedisModule_KeyType(key);
    if (type != REDISMODULE_KEYTYPE_EMPTY &&
        RedisModule_ModuleTypeGetType(key) != HelloType)
    {
        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
    }

    /* Parse the timeout before even trying to serve the client synchronously,
     * so that we always fail ASAP on syntax errors. */
    long long timeout;
    if (RedisModule_StringToLongLong(argv[4],&timeout) != REDISMODULE_OK) {
        return RedisModule_ReplyWithError(ctx,
            "ERR invalid timeout parameter");
    }

    /* Can we serve the reply synchronously? */
    if (type != REDISMODULE_KEYTYPE_EMPTY) {
        return HelloTypeRange_RedisCommand(ctx,argv,argc-1);
    }

    /* Otherwise let's block on the key. */
    void *privdata = RedisModule_Alloc(100);
    RedisModule_BlockClientOnKeys(ctx,HelloBlock_Reply,HelloBlock_Timeout,HelloBlock_FreeData,timeout,argv+1,1,privdata);
    return REDISMODULE_OK;
}

/* ========================== "hellotype" type methods ======================= */

void *HelloTypeRdbLoad(RedisModuleIO *rdb, int encver) {
    if (encver != 0) {
        /* RedisModule_Log("warning","Can't load data with version %d", encver);*/
        return NULL;
    }
    uint64_t elements = RedisModule_LoadUnsigned(rdb);
    struct HelloTypeObject *hto = createHelloTypeObject();
    while(elements--) {
        int64_t ele = RedisModule_LoadSigned(rdb);
        HelloTypeInsert(hto,ele);
    }
    return hto;
}

void HelloTypeRdbSave(RedisModuleIO *rdb, void *value) {
    struct HelloTypeObject *hto = value;
    struct HelloTypeNode *node = hto->head;
    RedisModule_SaveUnsigned(rdb,hto->len);
    while(node) {
        RedisModule_SaveSigned(rdb,node->value);
        node = node->next;
    }
}

void HelloTypeAofRewrite(RedisModuleIO *aof, RedisModuleString *key, void *value) {
    struct HelloTypeObject *hto = value;
    struct HelloTypeNode *node = hto->head;
    while(node) {
        RedisModule_EmitAOF(aof,"HELLOTYPE.INSERT","sl",key,node->value);
        node = node->next;
    }
}

/* The goal of this function is to return the amount of memory used by
 * the HelloType value. */
size_t HelloTypeMemUsage(const void *value) {
    const struct HelloTypeObject *hto = value;
    struct HelloTypeNode *node = hto->head;
    return sizeof(*hto) + sizeof(*node)*hto->len;
}

void HelloTypeFree(void *value) {
    HelloTypeReleaseObject(value);
}

void HelloTypeDigest(RedisModuleDigest *md, void *value) {
    struct HelloTypeObject *hto = value;
    struct HelloTypeNode *node = hto->head;
    while(node) {
        RedisModule_DigestAddLongLong(md,node->value);
        node = node->next;
    }
    RedisModule_DigestEndSequence(md);
}

/* This function must be present on each Redis module. It is used in order to
 * register the commands into the Redis server. */
int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
    REDISMODULE_NOT_USED(argv);
    REDISMODULE_NOT_USED(argc);

    if (RedisModule_Init(ctx,"hellotype",1,REDISMODULE_APIVER_1)
        == REDISMODULE_ERR) return REDISMODULE_ERR;

    RedisModuleTypeMethods tm = {
        .version = REDISMODULE_TYPE_METHOD_VERSION,
        .rdb_load = HelloTypeRdbLoad,
        .rdb_save = HelloTypeRdbSave,
        .aof_rewrite = HelloTypeAofRewrite,
        .mem_usage = HelloTypeMemUsage,
        .free = HelloTypeFree,
        .digest = HelloTypeDigest
    };

    HelloType = RedisModule_CreateDataType(ctx,"hellotype",0,&tm);
    if (HelloType == NULL) return REDISMODULE_ERR;

    if (RedisModule_CreateCommand(ctx,"hellotype.insert",
        HelloTypeInsert_RedisCommand,"write deny-oom",1,1,1) == REDISMODULE_ERR)
        return REDISMODULE_ERR;

    if (RedisModule_CreateCommand(ctx,"hellotype.range",
        HelloTypeRange_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
        return REDISMODULE_ERR;

    if (RedisModule_CreateCommand(ctx,"hellotype.len",
        HelloTypeLen_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
        return REDISMODULE_ERR;

    if (RedisModule_CreateCommand(ctx,"hellotype.brange",
        HelloTypeBRange_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
        return REDISMODULE_ERR;

    return REDISMODULE_OK;
}