Redis Integration Layer

This repository contains a Helper-class in C++ in order to integrate the Redis-datastore in C++ applications.

The code depends on two third-party libraries:

• libev
• hiredis

Following features are supported:

• Load scripts from a given scriptdir.
• Register call back functions for pub-sub or keyspace-notifications
• Simple and complete interface to the RedisContext from hiredis.

Code Example

In order to get a feeling for how the hiredis-client works read its README.md.

Load scripts from a directory

// Connect to redis-instance...
Redis::Integration::RedisHelper rh("127.0.0.1",6379,500000);
std::cout << "Database connection ... establishing..." << std::endl;
if(rh.connect() != 0)
{
	std::cout << "Redis Connection Failed - Fatal Error" << std::endl;
	exit(1);
}
std::cout << "Connected to database - preparing environment..." << std::endl;
int scripts_loaded = rh.loadScriptDir("./scripts","*.lua");
std::cout << "Loaded " << scripts_loaded << " db-scripts." << std::endl;

Save a key in the datastore

// Use the RedisHelper to connect to Redis...
Redis::Integration::RedisHelper rh("127.0.0.1",6379,500000);
int connection_status = rh.connect();
if(connection_status != 0)
{
  std::cout << rh.lastError() << std::endl;
}
else
{
  // Call the Script by name and pass the parameters
  redisReply *reply = (redisReply*)redisCommand(
    rh.getRedisContext(),
    "EVALSHA f49ae33bd0d21475b52cdf677bc762f5cc0f856f 2 SomeEntity %d-%d %s",
    input.getA(),
    input.getB(),
    input.toJsonString().c_str()
);
freeReplyObject(reply);
// RedisHelper will destroy the Context upon Destruction
}

for more examples, take a look at the tests.

Register a Callback for a key-space notification

// Define the callback-function.....
void triggerOnSomePrefixEvents(redisAsyncContext *c, void *reply, void *privdata) {
    redisReply *r = (redisReply *)reply;
    if (reply == NULL) return;

    printf("SomePrefix: Got a message... of type: %d\n",r->type);
    if (r->type == REDIS_REPLY_ARRAY) {
        unsigned int j = 0;
        for (j = 0; j < r->elements; j++) {
            printf("%u) %s\n", j, r->element[j]->str);
        }
    }

    if(r->type == REDIS_REPLY_STRING)
      printf("%s\n",r->str);
}

Redis::Integration::RedisHelper rnotifier("127.0.0.1",6379,500000);
// EA - see explanation at https://redis.io/topics/notifications#configuration
rnotifier.registerCallback("event",0,"SomePrefix:*",triggerOnSomePrefixEvents);
rnotifier.runLoop("EA");

Motivation

After seeing some other client-packages such as redis3m which are really good, a simpler interface was needed for some projects.

You should look at those first, since we wanted a library which could run on very limited hardware and for these platforms we do not have recent compilers supporting C11 etc, this stripped down version was created.

Installation

This library is compiled by using autoconf and pkg-config. The library runs on:

• Ubuntu (debian)
  • 12.04 / 14.04 / (16.04 need to check)

The basic compile steps are:

• prep your environment
• build/install sub-packages
• compile RedisILayer

Compile all local

# createbd.sh - Create Build-directory will:
# 1. Creates a local builddeps-directory -- $BD
# 2. Downloads and installs libev from source in 1.
# 3. Downloads and installs hiredis from source in 1.
. createbd.sh
./autogen.sh --prefix $BD
make
make check
make install

Install ubuntu package compile RedisILayer-local

sudo apt-get install libev hiredis-dev
./autogen.sh --prefix $BD
make
make check
make install

Tests

make check

Examples

See the RedisILayer-tests

Contributors

• Fabian N.C. van 't Hooft

License

• libev-LICENSE
• hiredis-COPYING