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.