https://github.com/sewenew/redis-protobuf
Redis module for reading and writing Protobuf messages
https://github.com/sewenew/redis-protobuf
protobuf redis redis-module redis-protobuf
Last synced: 11 months ago
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Redis module for reading and writing Protobuf messages
- Host: GitHub
- URL: https://github.com/sewenew/redis-protobuf
- Owner: sewenew
- License: apache-2.0
- Created: 2019-05-09T14:38:30.000Z (about 7 years ago)
- Default Branch: master
- Last Pushed: 2022-06-13T14:05:00.000Z (about 4 years ago)
- Last Synced: 2024-12-10T02:10:38.808Z (over 1 year ago)
- Topics: protobuf, redis, redis-module, redis-protobuf
- Language: C++
- Homepage:
- Size: 585 KB
- Stars: 204
- Watchers: 12
- Forks: 22
- Open Issues: 9
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# redis-protobuf
[中文交流群](http://github.com/sewenew/redis-protobuf/blob/master/Chinese.md)
- [Overview](#overview)
- [Motivation](#motivation)
- [Installation](#installation)
- [Run redis-protobuf With Docker](#run-redis-protobuf-with-docker)
- [Install redis-protobuf With Source Code](#install-redis-protobuf-with-source-code)
- [Load redis-protobuf](#load-redis-protobuf)
- [Getting Started](#getting-started)
- [redis-cli](#redis-cli)
- [C++ Client](#c-client)
- [Python Client](#python-client)
- [Commands](#commands)
- [Path](#path)
- [PB.SET](#pbset)
- [PB.GET](#pbget)
- [PB.DEL](#pbdel)
- [PB.APPEND](#pbappend)
- [PB.LEN](#pblen)
- [PB.CLEAR](#pbclear)
- [PB.MERGE](#pbmerge)
- [PB.TYPE](#pbtype)
- [PB.SCHEMA](#pbschema)
- [Author](#author)
## Overview
This is a [Redis Module](https://redis.io/topics/modules-intro) for reading and writing protobuf messages (only support Protobuf version 3, i.e. `syntax="proto3";`).
**NOTE**: In order to use this module, you should read the [Protobuf doc](https://developers.google.com/protocol-buffers) to learn how to define a protobuf message.
**NOTE**: I'm not a native speaker. So if the documentation is unclear, please feel free to open an issue or pull request. I'll response ASAP.
### Motivation
Redis supports multiple data structures, such as string, list, and hash. In order to keep things simple, Redis doesn't support nested data structures, e.g. you cannot have a list whose element is a list. However, sometimes nested data structures are useful, and [RedisJSON](https://github.com/RedisJSON/RedisJSON) is an option. With *RedisJSON*, you can save JSON object into Redis, and read and write JSON fields with that module. Since JSON can be nested, you can define your own nested data structure.
In fact, *redis-protobuf* is inspired by *RedisJSON*.
Both JSON and Protobuf are methods for serializing structured data. You can find many articles comparing these methods. Basically, Protobuf is faster and smaller than JSON, while JSON is more human friendly, since the former is binary while the latter is text. Also, you can convert a Protobuf to JSON and vice versa.
In order to make the nested data structure fast and memory efficient, I wrote this *redis-protobuf* module. With this module, you can define a Protobuf message, and *redis-protobuf* will use reflection to read and write message fields.
## Installation
### Run redis-protobuf With Docker
Run the following command to start *redis-protobuf* with Docker.
```
docker run -p 6379:6379 sewenew/redis-protobuf:latest
```
In this case, Docker runs Redis with a *redis.conf* file located at */usr/lib/redis/conf/redis.conf*. Also, you should put your *.proto* files in */usr/lib/redis/proto* directory. However, by default, the Docker image ships with an [example.proto](https://github.com/sewenew/redis-protobuf/blob/master/docker/example.proto) file, so that you can run the following examples without creating extra *.proto* files.
After running the Docker image, you can go to the [Getting Started section](#getting-started) to see how to run *redis-protobuf* commands.
### Install redis-protobuf With Source Code
You can also install redis-protobuf with source code.
#### Install Protobuf
First of all, you need to install Protobuf-C++. However, [the offical release](https://github.com/protocolbuffers/protobuf) doesn't expose reflection API for fields of map type (see [this issue](https://github.com/protocolbuffers/protobuf/issues/1322) for detail). So I modified the code to expose some internal interfaces. I published the modified code with *redis-protobuf* release, and you can download it from [here](https://github.com/sewenew/redis-protobuf/releases/download/0.0.1/protobuf-3.8.0-map-reflection.tar.gz). Also, you can check the *CHANGES-BY-SEWENEW.md* file for detail on what I've modifed.
Install modified Protobuf with the following commands:
```
curl -L -k https://github.com/sewenew/redis-protobuf/releases/download/0.0.1/protobuf-3.8.0-map-reflection.tar.gz -o protobuf-3.8.0-map-reflection.tar.gz
tar xfz protobuf-3.8.0-map-reflection.tar.gz
cd protobuf-3.8.0-map-reflection
./configure "CFLAGS=-fPIC" "CXXFLAGS=-fPIC"
make -j 4
make install
```
If you want to install Protobuf at a non-default location, you can specify the `--prefix=/path/to/install/location` option.
```
./configure "CFLAGS=-fPIC" "CXXFLAGS=-fPIC" --prefix=/usr
```
**NOTE**: You must specify the `"CFLAGS=-fPIC" "CXXFLAGS=-fPIC"` options when compiling Protobuf.
#### Install redis-protobuf
*redis-protobuf* is built with [CMAKE](https://cmake.org).
```
git clone https://github.com/sewenew/redis-protobuf.git
cd redis-protobuf
mkdir compile
cd compile
cmake ..
make
```
If Protobuf is installed at non-default location, you should use `CMAKE_PREFIX_PATH` to specify the installation path of Protobuf.
```
cmake -DCMAKE_PREFIX_PATH=/path/to/Protobuf ..
```
When `make` is done, you should find *libredis-protobuf.so* (or *libredis-protobuf.dylib* on MacOS) under the *redis-protobuf/compile* directory.
### Load redis-protobuf
Redis Module is supported since Redis 4.0, so you must install Redis 4.0 or above.
In order to load *redis-protobuf*, you need to modify the *redis.conf* file to add the `loadmodule` directive:
```
loadmodule /path/to/libredis-protobuf.so --dir proto-directory
```
*proto-directory* is the directory where your *.proto* files located. You must ensure that the directory exists and put your *.proto* files in this directory, so that *redis-protobuf* can load these *.proto* files dynamically. Also, if you want to use the standard *.proto* files, such as *google/protobuf/timestamp.proto*, *google/protobuf/struct.proto*, you also need to copy [these](https://github.com/sewenew/redis-protobuf/tree/master/docker/google/protobuf) standard proto files to *proto-directory*. Check [this](https://github.com/sewenew/redis-protobuf/issues/13) and [this](https://github.com/sewenew/redis-protobuf/issues/14) issues for detail.
Now, you can start your Redis instance:
```
redis-server /path/to/redis.conf
```
If Redis loads the module successfully, you can get the following message from the log:
```
Module 'PB' loaded from /path/to/libredis-protobuf.so
```
**NOTE**: If any of the given *.proto* file is invalid, Redis fails to load the module.
#### Possible Errors
If Redis fails to load *redis-protobuf*, and print the following error message:
```
undefined symbol: deflateInit2_
```
You can try [this solution](https://github.com/sewenew/redis-protobuf/issues/16).
#### redis-protobuf Options
## Getting Started
After [loading the module](#load-redis-protobuf), you can use any Redis client to send *redis-protobuf* [commands](#Commands).
We'll use the following *.proto* file as example, unless otherwise stated. In order to test examples in this doc, you need to put the following *.proto* file in the *proto-directory*.
**NOTE**: The [Docker image](https://cloud.docker.com/repository/docker/sewenew/redis-protobuf) also ships with this *.proto* file. So you can run the following examples with Docker too.
```
syntax = "proto3";
message SubMsg {
string s = 1;
int32 i = 2;
}
message Msg {
int32 i = 1;
SubMsg sub = 2;
repeated int32 arr = 3;
}
```
As we mentioned before, *redis-protobuf* only supports Protobuf version 3. So you must put `syntax = "proto3";` at the beginning of your *.proto* file.
### redis-cli
The following examples use the offical Redis client, i.e. *redis-cli*, to send *redis-protobuf* commands.
List module info:
```
127.0.0.1:6379> MODULE LIST
1) 1) "name"
2) "PB"
3) "ver"
4) (integer) 1
```
Set message:
```
127.0.0.1:6379> PB.SET key Msg '{"i" : 1, "sub" : {"s" : "string", "i" : 2}, "arr" : [1, 2, 3]}'
(integer) 1
```
**NOTE**: As we mentioned before, Protobuf is not human friendly. So *redis-protobuf* also supports setting JSON string as value, and the module will convert the JSON string to Protobuf message automatically. Check the [C++ client section](c-client) to see an example of setting binary string as value.
Get message:
```
127.0.0.1:6379> PB.GET key --FORMAT JSON Msg
"{\"i\":1,\"sub\":{\"s\":\"string\",\"i\":2},\"arr\":[1,2,3]}"
```
Set fields:
```
127.0.0.1:6379> PB.SET key Msg /i 10
(integer) 1
127.0.0.1:6379> PB.SET key Msg /sub/s redis-protobuf
(integer) 1
127.0.0.1:6379> PB.SET key Msg /arr/0 2
(integer) 1
```
Get fields:
```
127.0.0.1:6379> PB.GET key Msg /i
(integer) 10
127.0.0.1:6379> PB.GET key Msg /sub/s
"redis-protobuf"
127.0.0.1:6379> PB.GET key Msg /arr/0
(integer) 2
127.0.0.1:6379> PB.GET key --FORMAT JSON Msg /sub
"{\"s\":\"redis-protobuf\",\"i\":2}"
```
Delete message:
```
127.0.0.1:6379> PB.DEL key Msg
(integer) 1
```
### C++ Client
If you are using C++, you can use [redis-plus-plus](https://github.com/sewenew/redis-plus-plus) to send *redis-protobuf* commands:
```C++
try {
auto redis = Redis("tcp://127.0.0.1");
// Set Protobuf message.
Msg msg;
msg.set_i(1);
auto *sub = msg.mutable_sub();
sub->set_s("string");
sub->set_i(2);
msg.add_arr(1);
msg.add_arr(2);
msg.add_arr(3);
// Serialize Protobuf message.
std::string s;
if (!msg.SerializeToString(&s)) {
throw Error("failed to serialize protobuf message");
}
// Set value with the serialized message.
assert(redis.command("PB.SET", "key", "Msg", s) == 1);
// Get the message in binary format.
s = redis.command("PB.GET", "key", "--FORMAT", "BINARY", "Msg");
// Create a new message with the binary string.
Msg msg_new;
if (!msg_new.ParseFromString(s)) {
throw Error("failed to parse string to protobuf message");
}
// Set and get a message field.
assert(redis.command("PB.SET", "key", "Msg", "/i", 10) == 1);
assert(redis.command("PB.GET", "key", "Msg", "/i") == 10);
// Set and get a nested message field.
assert(redis.command("PB.SET", "key", "Msg", "/sub/s", "redis-protobuf") == 1);
assert(redis.command("PB.GET", "key", "Msg", "/sub/s") == "redis-protobuf");
// Delete the message.
assert(redis.command("PB.DEL", "key", "Msg") == 1);
} catch (const Error &e) {
// Error handling
}
```
### Python Client
If you are using Python, you can use [redis-py](https://github.com/andymccurdy/redis-py) to send *redis-protobuf* commands:
```
>>> import redis
>>> r = redis.StrictRedis(host='localhost', port=6379, db=0)
>>> r.execute_command('PB.SET', 'key', 'Msg', '{"i" : 1, "sub" : {"s" : "string", "i" : 2}, "arr" : [1, 2, 3]}')
1
>>> r.execute_command('PB.GET', 'key', '--FORMAT', 'BINARY', 'Msg')
b'\x08\x01\x12\n\n\x06string\x10\x02\x1a\x03\x01\x02\x03'
>>> r.execute_command('PB.GET', 'key', '--FORMAT', 'JSON', 'Msg')
b'{"i":1,"sub":{"s":"string","i":2},"arr":[1,2,3]}'
>>> r.execute_command('PB.SET', 'key', 'Msg', '/i', 2)
1
>>> r.execute_command('PB.GET', 'key', 'Msg', '/i')
2
>>> r.execute_command('PB.SET', 'key', 'Msg', '/sub/s', 'redis-protobuf')
1
>>> r.execute_command('PB.GET', 'key', 'Msg', '/sub/s')
b'redis-protobuf'
>>> r.execute_command('PB.SET', 'key', 'Msg', '/arr/0', 100)
1
>>> r.execute_command('PB.GET', 'key', 'Msg', '/arr/0')
100
```
## Commands
### Type and Path
Most commands have *type* and *path* as arguments, which specifies the message type and field. We use *JSON Pointer*: [RFC 6901](https://datatracker.ietf.org/doc/html/rfc6901) to specify the *path*. I'll use the following *.proto* file as an example to show you how to specify *type* and *path*.
**NOTE**: *path* IS CASE SENSITIVE.
```
syntax = "proto3";
package redis.pb;
message SubMsg {
string s = 1;
}
message Msg {
int32 i = 1;
SubMsg sub = 2;
repeated string str_arr = 3;
repeated SubMsg msg_arr = 4;
map m = 5;
};
```
#### Type
*Type* is the type name of a protobuf message. If you specify package name in the *.proto* definition, e.g. `package redis.pb`, you must also specify the pacakge name as a part of the type name, separated with a dot, i.e. '.'. For example, we can use the following to specify the type the message:
```
redis.pb.Msg
```
However, if you don't specify package name in the *.proto* definition, you can use the message type directly without any prefix.
### Path
With JSON Pointer, you can use `/` to address the field (and nested field) of a message.
```
/i
/sub
/sub/s
```
If the field is an array, you can use array index (seperated by '/'), i.e. `/i`, to specify the ith element. If the element is of message type, you can use '/' to specify the field of the element:
```
/str_arr/2
/msg_arr/1/s
```
The index is 0-based, and if the index is out-of-range, *redis-protobuf* will reply with an error.
If the field is a map, you can use a key (seperated by '/'), i.e. `/key`, to specify the corresponding value. If the value of message type, again, you can use a '/' to specify the field of the value:
```
/m/key
/m/key/s
```
### PB.SET
#### Syntax
```
PB.SET key [--NX | --XX] [--EX seconds | --PX milliseconds] type [path] value
```
- If the *path* is omitted, set the whole message with the given *value*.
- Otherwise, set the corresponding field with the given *value*.
**NOTE**: Since Protobuf fields are optional, when setting the whole message, you can only set parts of fields of this message. The following example only sets `/i` field, and leave other fields unset.
```
127.0.0.1:6379> PB.SET key Msg '{"i" : 1}'
(integer) 1
```
Protobuf message has pre-defined schema, so the *value* should match the type of the corresponding field.
- If the field is of integer type, i.e. `int32`, `int64`, `uint32`, `uint64`, `sint32`, `sint64`, `fixed32`, `fixed64`, `sfixed32`, `sfixed64`, the *value* string should be converted to the corresponding integer.
- If the field is of floating-point type, i.e. `float`, `double`, the *value* string should be converted to the corresponding floating-point number.
- If the field is of boolean type, i.e. `bool`, the *value* string should be *true* or *false*, or an integer (`0` is `false`, none `0` is `true`).
- If the field is of string type, i.e. `string`, `byte`, the *value* string can be any binary string.
- If the field is of enum type, i.e. `enum`, the *value* string should be converted to an integer.
- If the field is of message type, the *value* string should be a binary string that serialized from the corresponding Protobuf message, or a JSON string that can be converted to the corresponding Protobuf message.
#### Options
- **--NX**: Only set the key if it doesn't exist.
- **--XX**: Only set the key if it already exists.
- **--EX seconds**: Set the key with the specified expiration in seconds.
- **--PX milliseconds**: Set the key with the specified expiration in milliseconds.
#### Return Value
Integer reply: 1 if set successfully. 0, otherwise, e.g. option *--NX* has been set, while the key already exists.
#### Error
Return an error reply in the following cases:
- The field specified by *path*, doesn't exist.
- *type* doesn't match the type of the message saved in *key*, i.e. try to overwrite a *key*, in which the message is of a different type. See the examples part for an example.
- *value* doesn't match the type of the field.
#### Time Complexity
O(1)
#### Examples
```
127.0.0.1:6379> PB.SET key Msg '{"i" : 1, "sub" : {"s" : "string", "i" : 2}, "arr" : [1, 2, 3]}'
(integer) 1
127.0.0.1:6379> PB.SET key Msg /i 10
(integer) 1
127.0.0.1:6379> PB.SET key Msg /sub/s redis-protobuf
(integer) 1
127.0.0.1:6379> PB.SET key Msg /arr/0 2
(integer) 1
127.0.0.1:6379> PB.SET key SubMsg '{"s" : "hello"}'
(error) ERR type mismatch
```
### PB.GET
#### Syntax
```
PB.GET key [--FORMAT BINARY|JSON] type [path]
```
- If *path* is omitted, return the whole message in *key*.
- Otherwise, return the value of that field.
#### Options
- **--FORMAT**: If the field at *path* is of message type, this option specifies the format of the return value. If the field is of other types, this option is ignored.
- **BINARY**: return the value as a binary string by serializing the Protobuf message.
- **JSON**: return the value as a JSON string by converting the Protobuf message to JSON.
#### Return Value
Reply type is depends on the type of the field at *path*.
- Integer reply: if the field is of integer or enum type.
- Bulk string reply: if the field is of string or message type.
- Simple string reply: if the field is of boolean or floating-point type.
- Array reply: if the field is repeated or map type.
- Nil reply: if *key* doesn't exist.
#### Error
Return an error reply in the following cases:
- If the field specified by *path*, doesn't exist.
- If the specified type doesn't match the type of the message saved in *key*.
#### Time Complexity
O(1)
#### Examples
```
127.0.0.1:6379> PB.GET key --FORMAT BINARY Msg
"\b\n\x12\x12\n\x0eredis-protobuf\x10\x02\x1a\x03\x02\x02\x03"
127.0.0.1:6379> PB.GET key --FORMAT JSON Msg
"{\"i\":10,\"sub\":{\"s\":\"redis-protobuf\",\"i\":2},\"arr\":[2,2,3]}"
127.0.0.1:6379> PB.GET key Msg /i
(integer) 10
127.0.0.1:6379> PB.GET key --FORMAT JSON Msg /sub
"{\"s\":\"redis-protobuf\",\"i\":2}"
127.0.0.1:6379> PB.GET key Msg /arr/0
(integer) 2
127.0.0.1:6379> PB.GET key Msg /arr
1) (integer) 2
2) (integer) 2
3) (integer) 3
```
### PB.DEL
#### Syntax
```
PB.DEL key type [path]
```
- If *path* specifies an array element, e.g. `/arr/0`, delete the corresponding element from the array.
- If *path* specifies a map value, e.g. `/m/key`, delete the corresponding key-value pair from the map.
- If *path* is omitted, delete the key.
#### Return Value
Integer reply: 1 if *key* exists, 0 othewise.
#### Error
Return an error reply in the following cases:
- The field specified by *path*, doesn't exist
- The field is not an array element or a map value.
- The specifies *type* doesn't match the type of the message saved in *key*.
#### Time Complexity
- Delete array element: O(N), and N is the length of the array.
- Delete map element: O(1)
- Delete message: O(1)
#### Examples
```
127.0.0.1:6379> PB.DEL key Msg /arr/0
(integer) 1
127.0.0.1:6379> PB.DEL key Msg
(integer) 1
```
### PB.APPEND
#### Syntax
```
PB.APPEND key type path element [element, element...]
```
- If the field at *path* is a string, append *value* string to the field.
- If the field at *path* is an array, append the *value* as an element to the array.
If *key* doesn't exist, create an empty message, and do the append operation to the new message.
#### Return Value
Integer reply: The length of the string or the size of the array after the append operation.
#### Error
Return an error reply in the following cases:
- The field specified by *path*, doesn't exist.
- The field at *path* is not a string or array.
#### Time Complexity
Amortized O(1)
#### Examples
```
127.0.0.1:6379> pb.append key Msg /sub/s WithTail
(integer) 14
127.0.0.1:6379> pb.append key Msg /arr 4
(integer) 4
```
### PB.LEN
#### Syntax
```
PB.LEN key type [path]
```
- If the field at *path* is a string, return the length of the string.
- If the field at *path* is an array, return the size of the array.
- If the field at *path* is a map, return the size of the map.
- If the field at *path* is a message, return the length of the serialized binary string of the message.
- If *path* is omitted, return the length of the serialized binary string of whole message.
#### Return Value
Integer reply: 0 if *key* doesn't exist. Otherwise, the length of the string/array/map/message.
#### Error
Return an error reply in the following cases:
- *path* doesn't exist.
- The field at *path* is not a string/array/map/message.
#### Time Complexity
O(1)
#### Examples
```
127.0.0.1:6379> PB.LEN key Msg
(integer) 28
127.0.0.1:6379> PB.LEN key Msg /sub/s
(integer) 14
127.0.0.1:6379> PB.LEN key Msg /arr
(integer) 4
```
### PB.CLEAR
#### Syntax
```
PB.CLEAR key type [path]
```
- If *path* specifies a message type, clear the message in *key*.
- If *path* specifies a field, clear the field.
- If *path* is omitted, clear the whole message, NOT delete!
Please check the Protubuf doc for the definition of **clear**.
#### Return Value
Integer reply: 1 if the *key* exists, 0 otherwise.
#### Error
Return an error reply in the following cases:
- The specified *type* doesn't match the type of the message saved in *key*.
- *path* doesn't exist.
#### Time Complexity
O(1)
#### Examples
```
127.0.0.1:6379> PB.CLEAR key Msg
(integer) 1
127.0.0.1:6379> PB.CLEAR key Msg /arr
(integer) 1
127.0.0.1:6379> PB.CLEAR non-exist-key Msg
(integer) 0
```
### PB.MERGE
#### Syntax
```
PB.MERGE key type [path] value
```
- If *path* specifies a field, merge the *value* into the field.
- If *key* doesn't exist, this command behaves as *PB.SET*.
- If *path* is omitted, parse *value* to a message, and merge it into the message in *key*.
Please check the Protubuf doc for the definition of **merge**.
#### Return Value
Integer reply: 1 if the *key* exists, 0 otherwise.
#### Error
Return an error reply in the following cases:
- The specified *type*, doesn't match the type of the message saved in *key*.
- *path* doesn't exist.
#### Time Complexity
O(1)
#### Examples
```
```
### PB.TYPE
#### Syntax
```
PB.TYPE key
```
Get the message type of message in *key*.
#### Return Value
- Simple string reply: The Protobuf message type, if *key* exists.
- Nil reply: If *key* doesn't exist.
#### Time Complexity
O(1)
#### Examples
```
127.0.0.1:6379> PB.TYPE key
Msg
```
### PB.SCHEMA
#### Syntax
```
PB.SCHEMA type
```
Get the schema of the given Protobuf message *type*.
#### Return Value
- Bulk string reply: The schema of the given *type*.
- Nil reply: If the *type* doesn't exist.
#### Time Complexity
O(1)
#### Examples
```
127.0.0.1:6379> PB.SCHEMA Msg
"message Msg {\n int32 i = 1;\n SubMsg sub = 2;\n repeated int32 arr = 3;\n}\n"
```
### PB.IMPORT
#### Syntax
```
PB.IMPORT filename content
```
Import a protobuf file asynchronously. If the file has been imported successfully, the file will be persisted in `proto-directory`.
**NOTE**:
- Since this command runs asynchronously, you need to use [PB.LASTIMPORT](#pblastimport) to check the importing result.
- If a file has already been imported, you cannot re-import it with this command, i.e. you cannot update an already imported proto file. Instead, you need to update the file on disk, and restart Redis server.
#### Return Value
- Simple string reply: "OK"
#### Time Complexity
O(1)
#### Examples
```
127.0.0.1:6379> PB.IMPORT test.proto 'syntax="proto3"; message M { int32 i = 1; }'
OK
```
### PB.LASTIMPORT
#### Syntax
```
PB.LASTIMPORT
```
Get the importing result of all imported proto files since last call to this command.
Since `PB.IMPORT` runs asynchronously, the importing result will be recorded. When `PB.LASTIMPORT` is called, all these records will be returned to client, and these records will be cleared on the server side. So if you call `PB.LASTIMPORT` twice, without calling `PB.IMPORT` between these two calls of `PB.LASTIMPORT`, the second calls will return empty array reply.
#### Return Value
- Array reply: Status of last imported protobuf files. For each file, if it's imported successfully, the status is "OK". Otherwise, the status is an error message.
#### Time Complexity
O(1)
#### Examples
```
127.0.0.1:6379> PB.LASTIMPORT
1) 1) "msg1.proto"
2) "ERR failed to load msg1.proto\nerror:...
2) 1) "msg2.proto"
2) "OK"
```
## Author
*redis-protobuf* is written by [sewenew](https://github.com/sewenew), who is also active on [StackOverflow](https://stackoverflow.com/users/5384363/for-stack).