# HIREDIS
Hiredis is a minimalistic C client library for the [Redis](http://redis.io/) database.
It is minimalistic because it just adds minimal support for the protocol, but
at the same time it uses an high level printf-alike API in order to make it
much higher level than otherwise suggested by its minimal code base and the
lack of explicit bindings for every Redis command.
Apart from supporting sending commands and receiving replies, it comes with
a reply parser that is decoupled from the I/O layer. It
is a stream parser designed for easy reusability, which can for instance be used
in higher level language bindings for efficient reply parsing.
Hiredis only supports the binary-safe Redis protocol, so you can use it with any
Redis version >= 1.2.0.
The library comes with multiple APIs. There is the
*synchronous API*, the *asynchronous API* and the *reply parsing API*.
## UPGRADING
Version 0.9.0 is a major overhaul of hiredis in every aspect. However, upgrading existing
code using hiredis should not be a big pain. The key thing to keep in mind when
upgrading is that hiredis >= 0.9.0 uses a `redisContext*` to keep state, in contrast to
the stateless 0.0.1 that only has a file descriptor to work with.
## Synchronous API
To consume the synchronous API, there are only a few function calls that need to be introduced:
redisContext *redisConnect(const char *ip, int port);
void *redisCommand(redisContext *c, const char *format, ...);
void freeReplyObject(void *reply);
### Connecting
The function `redisConnect` is used to create a so-called `redisContext`. The
context is where Hiredis holds state for a connection. The `redisContext`
struct has an integer `err` field that is non-zero when an the connection is in
an error state. The field `errstr` will contain a string with a description of
the error. More information on errors can be found in the **Errors** section.
After trying to connect to Redis using `redisConnect` you should
check the `err` field to see if establishing the connection was successful:
redisContext *c = redisConnect("127.0.0.1", 6379);
if (c->err) {
printf("Error: %s\n", c->errstr);
// handle error
}
### Sending commands
There are several ways to issue commands to Redis. The first that will be introduced is
`redisCommand`. This function takes a format similar to printf. In the simplest form,
it is used like this:
reply = redisCommand(context, "SET foo bar");
The specifier `%s` interpolates a string in the command, and uses `strlen` to
determine the length of the string:
reply = redisCommand(context, "SET foo %s", value);
When you need to pass binary safe strings in a command, the `%b` specifier can be
used. Together with a pointer to the string, it requires a `size_t` length argument
of the string:
reply = redisCommand(context, "SET foo %b", value, valuelen);
Internally, Hiredis splits the command in different arguments and will
convert it to the protocol used to communicate with Redis.
One or more spaces separates arguments, so you can use the specifiers
anywhere in an argument:
reply = redisCommand(context, "SET key:%s %s", myid, value);
### Using replies
The return value of `redisCommand` holds a reply when the command was
successfully executed. When an error occurs, the return value is `NULL` and
the `err` field in the context will be set (see section on **Errors**).
Once an error is returned the context cannot be reused and you should set up
a new connection.
The standard replies that `redisCommand` are of the type `redisReply`. The
`type` field in the `redisReply` should be used to test what kind of reply
was received:
* **`REDIS_REPLY_STATUS`**:
* The command replied with a status reply. The status string can be accessed using `reply->str`.
The length of this string can be accessed using `reply->len`.
* **`REDIS_REPLY_ERROR`**:
* The command replied with an error. The error string can be accessed identical to `REDIS_REPLY_STATUS`.
* **`REDIS_REPLY_INTEGER`**:
* The command replied with an integer. The integer value can be accessed using the
`reply->integer` field of type `long long`.
* **`REDIS_REPLY_NIL`**:
* The command replied with a **nil** object. There is no data to access.
* **`REDIS_REPLY_STRING`**:
* A bulk (string) reply. The value of the reply can be accessed using `reply->str`.
The length of this string can be accessed using `reply->len`.
* **`REDIS_REPLY_ARRAY`**:
* A multi bulk reply. The number of elements in the multi bulk reply is stored in
`reply->elements`. Every element in the multi bulk reply is a `redisReply` object as well
and can be accessed via `reply->element[..index..]`.
Redis may reply with nested arrays but this is fully supported.
Replies should be freed using the `freeReplyObject()` function.
Note that this function will take care of freeing sub-replies objects
contained in arrays and nested arrays, so there is no need for the user to
free the sub replies (it is actually harmful and will corrupt the memory).
**Important:** the current version of hiredis (0.10.0) free's replies when the
asynchronous API is used. This means you should not call `freeReplyObject` when
you use this API. The reply is cleaned up by hiredis _after_ the callback
returns. This behavior will probably change in future releases, so make sure to
keep an eye on the changelog when upgrading (see issue #39).
### Cleaning up
To disconnect and free the context the following function can be used:
void redisFree(redisContext *c);
This function immediately closes the socket and then free's the allocations done in
creating the context.
### Sending commands (cont'd)
Together with `redisCommand`, the function `redisCommandArgv` can be used to issue commands.
It has the following prototype:
void *redisCommandArgv(redisContext *c, int argc, const char **argv, const size_t *argvlen);
It takes the number of arguments `argc`, an array of strings `argv` and the lengths of the
arguments `argvlen`. For convenience, `argvlen` may be set to `NULL` and the function will
use `strlen(3)` on every argument to determine its length. Obviously, when any of the arguments
need to be binary safe, the entire array of lengths `argvlen` should be provided.
The return value has the same semantic as `redisCommand`.
### Pipelining
To explain how Hiredis supports pipelining in a blocking connection, there needs to be
understanding of the internal execution flow.
When any of the functions in the `redisCommand` family is called, Hiredis first formats the
command according to the Redis protocol. The formatted command is then put in the output buffer
of the context. This output buffer is dynamic, so it can hold any number of commands.
After the command is put in the output buffer, `redisGetReply` is called. This function has the
following two execution paths:
1. The input buffer is non-empty:
* Try to parse a single reply from the input buffer and return it
* If no reply could be parsed, continue at *2*
2. The input buffer is empty:
* Write the **entire** output buffer to the socket
* Read from the socket until a single reply could be parsed
The function `redisGetReply` is exported as part of the Hiredis API and can be used when a reply
is expected on the socket. To pipeline commands, the only things that needs to be done is
filling up the output buffer. For this cause, two commands can be used that are identical
to the `redisCommand` family, apart from not returning a reply:
void redisAppendCommand(redisContext *c, const char *format, ...);
void redisAppendCommandArgv(redisContext *c, int argc, const char **argv, const size_t *argvlen);
After calling either function one or more times, `redisGetReply` can be used to receive the
subsequent replies. The return value for this function is either `REDIS_OK` or `REDIS_ERR`, where
the latter means an error occurred while reading a reply.
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C加载使用Redis数据库
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C加载使用Redis数据库 (206个子文件)
sentinel.c 117KB
redis.c 109KB
t_zset.c 70KB
networking.c 55KB
aof.c 54KB
ziplist.c 52KB
rdb.c 52KB
redis-cli.c 49KB
config.c 42KB
t_list.c 39KB
hiredis.c 39KB
replication.c 36KB
scripting.c 35KB
debug.c 29KB
win32_cow.c 29KB
t_set.c 27KB
dict.c 26KB
redis-benchmark.c 24KB
redis-check-dump.c 23KB
async.c 23KB
t_hash.c 23KB
db.c 23KB
test.c 23KB
sds.c 22KB
sort.c 20KB
object.c 18KB
anet.c 18KB
ae_wsiocp.c 17KB
sds.c 17KB
zipmap.c 17KB
util.c 16KB
net.c 16KB
intset.c 16KB
win32fixes.c 15KB
win32fixes.c 15KB
ae.c 15KB
bitops.c 15KB
t_string.c 15KB
win32_wsiocp.c 14KB
dict.c 12KB
multi.c 11KB
pubsub.c 11KB
ae_evport.c 11KB
zmalloc.c 10KB
crc64.c 10KB
adlist.c 10KB
bio.c 10KB
memtest.c 9KB
lzf_c.c 9KB
migrate.c 8KB
sha1.c 7KB
redis-check-aof.c 7KB
slowlog.c 7KB
syncio.c 6KB
pqsort.c 6KB
rio.c 6KB
win32_bksv.c 5KB
ae_epoll.c 5KB
ae_kqueue.c 4KB
lzf_d.c 4KB
rand.c 4KB
endianconv.c 4KB
ae_select.c 4KB
release.c 2KB
example.c 2KB
example-ae.c 1KB
example-libevent.c 1KB
example-libev.c 1KB
RedisDLL.vcxprojResolveAssemblyReference.cache 713B
COPYING 2KB
RedisOperation.cpp 8KB
RedisDemo.cpp 352B
stdafx.cpp 214B
RedisOperation.def 278B
Makefile.dep 6KB
RedisDLL.dll 70KB
RedisDLL.dll 31KB
RedisDemo.exe 7KB
RedisDLL.exp 1KB
RedisDLL.exp 1KB
RedisDemo.vcxproj.filters 1KB
RedisDLL.vcxproj.filters 1KB
.gitignore 57B
.gitignore 42B
redis.h 52KB
help.h 17KB
hiredis.h 9KB
win32fixes.h 8KB
dict.h 6KB
win32_cow.h 6KB
config.h 6KB
lzfP.h 5KB
async.h 5KB
rdb.h 5KB
dict.h 5KB
libev.h 4KB
ae.h 4KB
lzf.h 4KB
ae.h 4KB
libevent.h 4KB
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