ref: 5f7a6b7ea3c4ae1b51beffe3309e9b6b0491e71f
dir: /sys/man/2/venti-client/
.TH VENTI-CLIENT 2 .SH NAME vtconnect, vthello, vtread, vtwrite, vtreadpacket, vtwritepacket, vtsync, vtping, vtrpc, ventidoublechecksha1 \- Venti client .SH SYNOPSIS .ft L #include <u.h> .br #include <libc.h> .br #include <venti.h> .ta +\w'\fLPacket* 'u +\w'\fLxxxxxxxx'u .PP .B Packet* vtrpc(VtConn *z, Packet *p) .PP .B int vthello(VtConn *z) .PP .B int vtconnect(VtConn *z) .PP .B int vtread(VtConn *z, uchar score[VtScoreSize], .br .B uint type, uchar *buf, int n) .PP .B int vtwrite(VtConn *z, uchar score[VtScoreSize], .br .B uint type, uchar *buf, int n) .PP .B Packet* vtreadpacket(VtConn *z, uchar score[VtScoreSize], .br .B uint type, int n) .PP .B int vtwritepacket(VtConn *z, uchar score[VtScoreSize], .br .B uint type, Packet *p) .PP .B int vtsync(VtConn *z) .PP .B int vtping(VtConn *z) .PP .B extern int ventidoublechecksha1; /* default 1 */ .SH DESCRIPTION These routines execute the client side of the .IR venti (6) protocol. .PP .I Vtrpc executes a single Venti RPC transaction, sending the request packet .IR p and then waiting for and returning the response packet. .I Vtrpc will set the tag in the packet. .I Vtrpc frees .IR p , even on error. .I Vtrpc is typically called only indirectly, via the functions below. .PP .I Vthello executes a .B hello transaction, setting .IB z ->sid to the name used by the server. .I Vthello is typically called only indirectly, via .IR vtconnect . .PP .I Vtconnect calls .I vtversion (see .IR venti-conn (2)) and .IR vthello , in that order, returning success only if both succeed. This sequence (calling .I vtversion and then .IR vthello ) must be done before the functions below can be called. .PP .I Vtread reads the block with the given .I score and .I type from the server, stores the returned data in memory at .IR buf , and returns the number of bytes read. If the server's block has size larger than .IR n , .I vtread does not modify .I buf and returns an error. .PP .I Vtwrite writes the .I n bytes in .I buf as a block of the given .IR type , setting .IR score . .PP .I Vtreadpacket and .I vtwritepacket are like .I vtread and .I vtwrite but return or accept the block contents in the form of a .BR Packet . They avoid making a copy of the data. .PP .I Vtsync causes the server to flush all pending write requests to disk before returning. .PP .I Vtping executes a ping transaction with the server. .PP By default, .I vtread and .I vtreadpacket check that the SHA1 hash of the returned data matches the requested .IR score , and .I vtwrite and .I vtwritepacket check that the returned .I score matches the SHA1 hash of the written data. Setting .I ventidoublechecksha1 to zero disables these extra checks, mainly for benchmarking purposes. Doing so in production code is not recommended. .PP 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 .I vtsendproc and .I vtrecvproc as described in .IR venti-conn (2). .SH SOURCE .B /sys/src/libventi .SH SEE ALSO .IR venti (2), .IR venti-conn (2), .IR venti-packet (2), .IR venti (6) .SH DIAGNOSTICS .I Vtrpc and .I vtpacket return nil on error. The other routines return \-1 on error. .PP .I Vtwrite returns 0 on success: there are no partial writes.