format README.md

README.md

@@ -3,16 +3,94 @@ CascaDB
 
 Yet another write-optimized storage engine, using buffered B-tree algorithm inspired by TokuDB.
 
-Currently CascaDB provides a key-value read/write API similar to LevelDB.
+## Features
+* Provides a key-value access API similar to LevelDB.
+* Support Snappy compression.
+* Support Direct IO and Linux AIO.
 
 
-Compile
--------
+## Compile
 CascaDB utilizes CMake to build, so first of all you should install CMake.
 
 It's recommended to make out of source build, that is, object files are generated into a separated directory with the source directory.
 
-mkdir build
-cd build
-cmake ..
-make && make install
+        mkdir build
+        cd build
+        cmake ..
+        make && make install
+
+## Performance
+
+Running bin/db_bench to get detailed performance report of how CascaDB running on your machine.
+
+e.g. `bin/db_bench --num=1000000`, This will create and test on a database of a million records, each record has a 16 byte key, and a 100 byte value.
+
+### Write Performance
+``
+fillseq      :       1.020 micros/op;                 
+fillrandom   :       2.559 micros/op;                 
+``
+
+### Read Performance
+Read benchmark results after sequential insertions
+``
+readrandom   :       1.125 micros/op;                 
+readseq      :       1.282 micros/op;      
+``
+
+Read benchmark results after random insertions
+``
+readrandom   :       3.227 micros/op;                 
+readseq      :       1.295 micros/op;                 
+``
+
+## Have a try!
+
+1. Include the header file.
+
+        #include <cascadb/db.h>
+
+2. Open the database.
+
+        Options opts;
+        opts.dir = create_fs_directory("/tmp/db_bench");
+        opts.comparator = new LexcialComparator();
+        opts.compress = kSnappyCompress;
+
+        const char *dbname = "example";
+        DB *db = DB::open(dbname, opts);
+        if (!db) {
+          fprintf(stderr, "open error %s\n", dbname);
+          exit(1);
+        }
+
+3. Insert record.
+
+        if (!db->put("This is the key", "This is the value") {
+            fprintf(stderr, "put error\n");
+        }
+
+4. Read record.
+
+        Slice value;
+        if (!db->get("This is the key", value) {
+            fprintf(stderr, "get error\n");
+        }
+        fprintf(stdout, "the value is %s", value.to_string().c_str());
+
+5. Delete record.
+
+        if (!db->del("This is the key")) {
+            fprintf(stderr, "del error\n");
+        }
+
+6. Destory database.
+
+        delete db;
+        delete opts.comparator;
+        delete opts.dir;
+
+## TODO
+* Add forward and backward iteration over data.
+* Support more compression methods.
+* Implement write ahead log to ensure write operation is atomic.