Leveldb source code analysis 1

1. Introduction to leveldb

Leveldb is a key-value storage engine developed by Google and announced open source code with the BSD license.

2. leveldb download and Installation

Leveldb is hosted on Google code. You can use git to download the source code:

Plain code

1. Git clone https://code.google.com/p/leveldb/

Compile leveldb after the download is complete.

Plain code

1. CD leveldb
2. Make all

The libleveldb. A library file is generated. Copy the header file of leveldb to the plain code under/usr/include.

1. CP-R./include/leveldb/usr/include/

This completes leveldb installation.

3. leveldb client program example

The test procedure is as follows:

CPP Code

1. # Include <assert. h>
2. # Include <string>
3. # Include <leveldb/DB. h>
4. # Include <iostream>
7. Int main ()
8. {
9. // Open a database
10. Leveldb: DB * dB;
11. Leveldb: Options options;
12. Options. create_if_missing = true;
13. Leveldb: Status status = leveldb: DB: open (options, "/tmp/testdb", & dB );
14. Assert (status. OK ());
16. // Write <key1, value1>
17. Const int write_times = 10000;
18. Int I = 0;
19. STD: String key = "key ";
20. STD: string value = "value ";
21. Status = DB-> put (leveldb: writeoptions (), key, value );
22. Assert (status. OK ());
24. // Read value1 by key1
25. Status = DB-> get (leveldb: readoptions (), key, & value );
26. Assert (status. OK ());
27. STD: cout <value <STD: Endl;
29. // Delete Databse
30. Delete dB;
32. Return 0;
33. }

Copy the generated libleveldb. A to the same directory of the source file and compile the program:

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1. G ++-O test. cpp libleveldb. A-lpthread

The test executable file is generated. The test result is as follows:

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1. [Root @ mdss33 test] #./test
2. Value