From 77adf4cd648dce41f89469dd185deec6b6b53a0b Mon Sep 17 00:00:00 2001 From: Vikas Gorur Date: Wed, 18 Feb 2009 17:36:07 +0530 Subject: Added all files --- doc/booster.txt | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 doc/booster.txt (limited to 'doc/booster.txt') diff --git a/doc/booster.txt b/doc/booster.txt new file mode 100644 index 00000000000..684ac8965c4 --- /dev/null +++ b/doc/booster.txt @@ -0,0 +1,54 @@ +Introduction +============ +* booster is a LD_PRELOADable library which boosts read/write performance by bypassing fuse for + read() and write() calls. + +Requirements +============ +* fetch volfile from glusterfs. +* identify whether multiple files are from the same mount point. If so, use only one context. + +Design +====== +* for a getxattr, along with other attributes, fuse returns following attributes. + * contents of client volume-file. + * mount point. + +* LD_PRELOADed booster.so maintains an hash table storing mount-points and libglusterfsclient handles + so that handles are reused for files from same mount point. + +* it also maintains a fdtable. fdtable maps the fd (integer) returned to application to fd (pointer to fd struct) + used by libglusterfsclient. application is returned the same fd as the one returned from libc apis. + +* During fork, these tables are overwritten to enable creation of fresh glusterfs context in child. + +Working +======= +* application willing to use booster LD_PRELOADs booster.so which is a wrapper library implementing + open, read and write. + +* application should specify the path to logfile through the environment variable GLFS_BOOSTER_LOGFILE. If + not specified, logging is done to /dev/stderr. + +* open call does, + * real_open on the file. + * fgetxattr(fd). + * store the volume-file content got in the dictionary to a temparory file. + * look in the hashtable for the mount-point, if already present get the libglusterfsclient handle from the + hashtable. Otherwise get a new handle from libglusterfsclient (be careful about mount point not present in + the hashtable and multiple glusterfs_inits running simultaneously for the same mount-point there by using + multiple handles for the same mount point). + * real_close (fd). + * delete temporary volume-volfile. + * glusterfs_open (handle, path, mode). + * store the fd returned by glusterfs_open in the fdtable at the same index as the fd returned by real_open. + * return the index as fd. + +* read/write calls do, + * get the libglusterfsclient fd from fdtable. + * if found use glusterfs_read/glusterfs_write, else use real_read/real_write. + +* close call does, + * remove the fd from the fdtable. + +* other calls use real_calls. -- cgit