qiuzhenguang / blobcached

Blobcached is a memcached protocol-compatible cache server for blob on SSD.

Blobcached

Blobcached is a memcached protocol-compatible cache server for blob on SSD.

Supported commands

Command	Format
get	get []+\r\n
set	set [noreply]\r\n\r\n
delete	delete [noreply]\r\n
touch	touch [noreply]\r\n
stats	stats\r\n

How it works

concepts

Name
indexfile	an indexfile contains many of items powered by blotdb
datafile	a regular file powered by mmap for storing values
item	an item is made up of key, offset, term, size anchoring the value in datafile
term	everytime the datafile is full, the term of datafile is increased

Command: Set

• get the offset and term of datafile
• write value to the datafile
• write item with the offset, term and key to the indexfile

Command: Get

• get the item by key
• check term and offset of the item against datafile
• read value from the datafile

Command: Touch

• implemented by get & set

GC

• Blobcached scans and removes expired or invalid items in the indexfile
• by default, the rate up to 32k items/second