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lock_client_cache.cc
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lock_client_cache.cc
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// RPC stubs for clients to talk to lock_server, and cache the locks
// see lock_client.cache.h for protocol details.
#include "lock_client_cache.h"
#include "rpc.h"
#include <sstream>
#include <iostream>
#include <stdio.h>
#include "tprintf.h"
#include "rpc/slock.h"
#include <time.h>
int lock_client_cache::last_port = 0;
lock_client_cache::lock_client_cache(std::string xdst,
class lock_release_user *_lu)
: lock_client(xdst), lu(_lu)
{
srand(time(NULL)^last_port);
rlock_port = ((rand()%32000) | (0x1 << 10));
const char *hname;
// VERIFY(gethostname(hname, 100) == 0);
hname = "127.0.0.1";
std::ostringstream host;
host << hname << ":" << rlock_port;
id = host.str();
last_port = rlock_port;
rpcs *rlsrpc = new rpcs(rlock_port);
rlsrpc->reg(rlock_protocol::revoke, this, &lock_client_cache::revoke_handler);
rlsrpc->reg(rlock_protocol::retry, this, &lock_client_cache::retry_handler);
//init mutex
pthread_mutex_init(&mu, NULL);
//init rpc addons
pthread_cond_init(&a_cond,NULL);
releasing = false;
delay = 10000; //nanosecs
//start outgoing thread
pthread_t th_out;
int rc = pthread_create(&th_out,NULL,dedicated,(void*)this);
if(rc){
tprintf("\nfailed to create outgoing thread\n");
exit(-1);
}
}
lock_protocol::status
lock_client_cache::acquire(lock_protocol::lockid_t lid)
{
// tprintf("\nacquire: attempting to acquire mutex\n");
ScopedLock sl(&mu);
tprintf("\nrecieved an acquire for lock %llu\n",lid);
tprintf("\nacquire is for client with id %s\n",id.c_str());
lock_map[lid].waiting++;
while(1){
if(lock_map[lid].local_state == FREE){
tprintf("\nlock was locally, free\n");
//give to thread
lock_map[lid].local_state = LOCKED;
lock_map[lid].waiting--;
return lock_protocol::OK;
}else if(lock_map[lid].rpc_state == ACQ || lock_map[lid].rpc_state == REL){
//go to wait
tprintf("\nclient is already acquiring or letting it go\n");
}else if(lock_map[lid].local_state == UNK){
//assert rpc_state = IDLE
tprintf("\nclient needs to get it from the server\n");
lock_map[lid].rpc_state = ACQ;
rpc_call call;
call.rpc = lock_client_cache::ACQUIRE;
call.lock_id = lid;
rpc_queue.enqueue(call);
tprintf("\nacquire call queued for later\n");
}
//enter wait
if(releasing){
tprintf("\nsignaling release call\n");
pthread_cond_signal(&a_cond);
}
tprintf("\nwaiting for lock\n");
pthread_cond_wait(&(lock_map[lid].cond),&mu);
tprintf("\nwaking up...\n");
}
}
lock_protocol::status
lock_client_cache::release(lock_protocol::lockid_t lid)
{
// tprintf("\nrelease: attempting to acquire mutex\n");
ScopedLock sl(&mu);
tprintf("\nrecieved a release for lock %llu on client %s\n",lid,id.c_str());
tprintf("\ngoing to delay a bit to see if anyone else wants it\n");
releasing = true;
clock_gettime(CLOCK_REALTIME, &tp);
tp.tv_nsec += delay;
int rc = 0;
while(lock_map[lid].waiting == 0 && rc == 0){
rc = pthread_cond_timedwait(&a_cond,&mu,&tp);
}
if(lock_map[lid].waiting>0){
//some threads want the lock
lock_map[lid].local_state = FREE;
pthread_cond_signal(&(lock_map[lid].cond));
return lock_protocol::OK;
}else if(lock_map[lid].rpc_state == REL){
//no one wants it, but the server so return it
lock_map[lid].local_state = UNK;
lock_map[lid].rpc_state = IDLE;
rpc_call call;
call.rpc = lock_client_cache::RELEASE;
call.lock_id = lid;
rpc_queue.enqueue(call);
return lock_protocol::OK;
}else{
//assert state is locked and idle
lock_map[lid].local_state = FREE;
return lock_protocol::OK;
}
}
rlock_protocol::status
lock_client_cache::revoke_handler(lock_protocol::lockid_t lid,
int &r)
{
tprintf("\nrevoke: attempting to acquire mutex %llu on client %s\n",lid,id.c_str());
//sets rpc state as releasing, so release will know to let return it.
ScopedLock sl(&mu);
tprintf("\nrecieved a revoke for lock %llu with %d threads waiting\n",lid,lock_map[lid].waiting);
//state should not be unknown (we have the lock)
if(lock_map[lid].local_state==LOCKED){
tprintf("\nit was locked, so it will return later\n");
//we are not done, just set state to releasing
lock_map[lid].rpc_state=REL;
}else{
tprintf("\nlock is free, so we'll return it.\n");
//we are done so return it
lock_map[lid].local_state = UNK;
lock_map[lid].rpc_state = IDLE;
rpc_call call;
call.rpc = lock_client_cache::RELEASE;
call.lock_id = lid;
rpc_queue.enqueue(call);
}
return rlock_protocol::OK;
}
rlock_protocol::status
lock_client_cache::retry_handler(lock_protocol::lockid_t lid,bool wait,
int &)
{
tprintf("\nretry: attempting to acquire mutex\n");
//sets the lock as free locally and signals a waiting thread
ScopedLock sl(&mu);
tprintf("\nrecieved a retry for lock %llu on client %s, %d threads are waiting\n",lid,id.c_str(),lock_map[lid].waiting);
//lock state should be unknown
lock_map[lid].rpc_state = wait ? REL : IDLE;
lock_map[lid].local_state = FREE;
pthread_cond_signal(&(lock_map[lid].cond));
return rlock_protocol::OK;
}
void
lock_client_cache::outgoing(){
//handles the thread safe queue and makes rpc calls
tprintf("\nstarted outgoing thread.\n");
int r;
while(1){
rpc_call rp = rpc_queue.dequeue();
tprintf("\nrpc call to be made\n");
if(rp.rpc == lock_client_cache::ACQUIRE){
tprintf("\nmaking acquire rpc call\n");
lock_protocol::status ret = cl->call(lock_protocol::acquire,rp.lock_id,id,r);
if(ret==lock_protocol::RETRY){
tprintf("\nacquire returned RETRY\n");
}else{
tprintf("\nacquire didnt return RETRY, error...\n");
}
}else{
//we have a release call to make
tprintf("\nmaking release rpc call\n");
//flushing extent cache
lu->dorelease(rp.lock_id);
lock_protocol::status ret = cl->call(lock_protocol::release,rp.lock_id,id,r);
}
}
}
void *
dedicated(void *lcc){
lock_client_cache* lc = (lock_client_cache*) lcc;
lc->outgoing();
}