Pfs_datanode
/* $Id: pfs_datanode.x 450 2011-10-11 12:30:40Z gerd $ -*- c -*- */
Datanode
Datanode access.
#include "pfs_types.x"
#ifndef PFS_DATANODE_X
#define PFS_DATANODE_X
program Datanode {
version V1 {
null
void null(void) = 0;
identity
mediumstring identity(mediumstring) = 1;Returns the identity of this node (an ID which is assigned anew when the datanode is initialized). The arg is the clustername. If the node belongs to the wrong cluster, this RPC must return
SYSTEM_ERR.
size
hyper size(void) = 2;Returns the number of blocks. The blocks have numbers from 0 to
size-1
blocksize
int blocksize(void) = 3;Returns the blocksize
clustername
mediumstring clustername(void) = 4;Returns the clustername
read
dn_channel_rd_data read (dn_channel_rd_req, hyper, int, int, ticket) = 5;
read(req, block, pos, len, ticket):
Reads a block, or a part of it. req defines how the data
is passed back to the caller (see docs for dn_channel_rd_req
in Pfs_types). The block is the block number of this
datanode. pos and len select a substring of this block.
ticket is the ticket returned by get_blocks.
Right now this ticket is not checked.
write
void write(hyper, dn_channel_wr_data, ticket) = 6;
write(block, contents, ticket):
Writes a block. It is only possible to write a block completely.
The block is the block number of this datanode.
In contents the data to write is passed. (See the docs
for dn_channel_wr_data in Pfs_types for details.)
The data in contents must have the length blocksize.
ticket is the ticket granting write access.
The safetrans ticket is checked!
copy
void copy(hyper, longstring, longstring, hyper, ticket, ticket) = 7;
copy(block, dest_node, dest_identity, dest_block, ticket,
dest_ticket):
Copies a block, possibly to a remote system. block identifies
the block on this datanode. dest_node is the datanode server
to where the block is written to. dest_identity is the
identity of the destination server. dest_block is the
block number of the destination server.
If dest_identity is equal to the own identity, this is a local
copy. Otherwise, dest_node is interpreted as "host:port", and the
block is written to the remote host.
ticket is the ticket granting read access to the block.
dest_ticket is the ticket granting write access to the block
on the destination datanode.
zero
void zero(hyper, ticket) = 8;
zero(block, ticket):
sync
void sync(void) = 9;Waits until the next sync cycle is done
alloc_shm_if_local
longstring_opt alloc_shm_if_local(void) = 10;If the client is on the same node, this RPC allocates a new POSIX shm object, and returns the path of this object. The object has zero size, and is created with mode 666. If the client is not on the same node, the RPC returns NULL.
The shm object exists only as long as the TCP connection persists (i.e. the client needs not to care about deleting it).
This method of shm-based communication is inherently insecure.
udsocket_if_local
longstring_opt udsocket_if_local(void) = 11;If the client is on the same node, this RPC may return the name of a Unix Domain socket to contact instead.
} = 1;
} = 0x8000d001;
#endif
