VENTI-CLIENT(2) VENTI-CLIENT(2)
NAME
vtconnect, vthello, vtread, vtwrite, vtreadpacket,
vtwritepacket, vtsync, vtping, vtrpc, ventidoublechecksha1 -
Venti client
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <venti.h>
Packet* vtrpc(VtConn *z, Packet *p)
int vthello(VtConn *z)
int vtconnect(VtConn *z)
int vtread(VtConn *z, uchar score[VtScoreSize],
uint type, uchar *buf, int n)
int vtwrite(VtConn *z, uchar score[VtScoreSize],
uint type, uchar *buf, int n)
Packet* vtreadpacket(VtConn *z, uchar score[VtScoreSize],
uint type, int n)
int vtwritepacket(VtConn *z, uchar score[VtScoreSize],
uint type, Packet *p)
int vtsync(VtConn *z)
int vtping(VtConn *z)
extern int ventidoublechecksha1; /* default 1 */
DESCRIPTION
These routines execute the client side of the venti(6) pro-
tocol.
Vtrpc executes a single Venti RPC transaction, sending the
request packet p and then waiting for and returning the
response packet. Vtrpc will set the tag in the packet.
Vtrpc frees p, even on error. Vtrpc is typically called
only indirectly, via the functions below.
Vthello executes a hello transaction, setting z->sid to the
name used by the server. Vthello is typically called only
indirectly, via vtconnect.
Vtconnect calls vtversion (see venti-conn(2)) and vthello,
in that order, returning success only if both succeed. This
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VENTI-CLIENT(2) VENTI-CLIENT(2)
sequence (calling vtversion and then vthello) must be done
before the functions below can be called.
Vtread reads the block with the given score and type from
the server, stores the returned data in memory at buf, and
returns the number of bytes read. If the server's block has
size larger than n, vtread does not modify buf and returns
an error.
Vtwrite writes the n bytes in buf as a block of the given
type, setting score.
Vtreadpacket and vtwritepacket are like vtread and vtwrite
but return or accept the block contents in the form of a
Packet. They avoid making a copy of the data.
Vtsync causes the server to flush all pending write requests
to disk before returning.
Vtping executes a ping transaction with the server.
By default, vtread and vtreadpacket check that the SHA1 hash
of the returned data matches the requested score, and
vtwrite and vtwritepacket check that the returned score
matches the SHA1 hash of the written data. Setting
ventidoublechecksha1 to zero disables these extra checks,
mainly for benchmarking purposes. Doing so in production
code is not recommended.
These functions can be called from multiple threads or procs
simultaneously to issue requests in parallel. Programs that
issue requests from multiple threads in the same proc should
start separate procs running vtsendproc and vtrecvproc as
described in venti-conn(2).
SOURCE
/sys/src/libventi
SEE ALSO
venti(2), venti-conn(2), venti-packet(2), venti(6)
DIAGNOSTICS
Vtrpc and vtpacket return nil on error. The other routines
return -1 on error.
Vtwrite returns 0 on success: there are no partial writes.
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