Fixed a race condition!

[invirt/third/libt4.git] / paxos.cc

diff --git a/paxos.cc b/paxos.cc
index b39fa5b..8b00ad8 100644 (file)
--- a/paxos.cc
+++ b/paxos.cc
@@ -20,7 +20,7 @@ bool majority(const nodes_t &l1, const nodes_t &l2) {
 // paxos_commit to inform higher layers of the agreed value for this
 // instance.
 
 // paxos_commit to inform higher layers of the agreed value for this
 // instance.
 

-proposer_acceptor::proposer_acceptor(class paxos_change *_delegate,
+proposer_acceptor::proposer_acceptor(paxos_change *_delegate,

         bool _first, const node_t & _me, const value_t & _value)
     : delegate(_delegate), me (_me)
 {
         bool _first, const node_t & _me, const value_t & _value)
     : delegate(_delegate), me (_me)
 {

@@ -48,12 +48,15 @@ bool proposer_acceptor::run(unsigned instance, const nodes_t & cur_nodes, const
     bool r = false;
     proposal.n = max(promise.n, proposal.n) + 1;
     nodes_t accepts;
     bool r = false;
     proposal.n = max(promise.n, proposal.n) + 1;
     nodes_t accepts;

-    value_t v = newv;
+    value_t v;

     if (prepare(instance, accepts, cur_nodes, v)) {
 
         if (majority(cur_nodes, accepts)) {
             LOG("received a majority of prepare responses");
 
     if (prepare(instance, accepts, cur_nodes, v)) {
 
         if (majority(cur_nodes, accepts)) {
             LOG("received a majority of prepare responses");
 

+            if (!v.size())
+                v = newv;
+

             breakpoint1();
 
             nodes_t nodes;
             breakpoint1();
 
             nodes_t nodes;

@@ -91,7 +94,7 @@ bool proposer_acceptor::prepare(unsigned instance, nodes_t & accepts,
         if (!r)
             continue;
         auto status = (paxos_protocol::status)r->call_timeout(
         if (!r)
             continue;
         auto status = (paxos_protocol::status)r->call_timeout(

-                paxos_protocol::preparereq, rpcc::to(1000), res, me, instance, proposal);
+                paxos_protocol::preparereq, milliseconds(100), res, me, instance, proposal);

         if (status == paxos_protocol::OK) {
             if (res.oldinstance) {
                 LOG("commiting old instance!");
         if (status == paxos_protocol::OK) {
             if (res.oldinstance) {
                 LOG("commiting old instance!");

@@ -122,7 +125,7 @@ void proposer_acceptor::accept(unsigned instance, nodes_t & accepts,
             continue;
         bool accept = false;
         int status = r->call_timeout(
             continue;
         bool accept = false;
         int status = r->call_timeout(

-                paxos_protocol::acceptreq, rpcc::to(1000), accept, me, instance, proposal, v);
+                paxos_protocol::acceptreq, milliseconds(100), accept, me, instance, proposal, v);

         if (status == paxos_protocol::OK && accept)
             accepts.push_back(i);
     }
         if (status == paxos_protocol::OK && accept)
             accepts.push_back(i);
     }

@@ -135,7 +138,7 @@ void proposer_acceptor::decide(unsigned instance, const nodes_t & accepts, const
         if (!r)
             continue;
         int res = 0;
         if (!r)
             continue;
         int res = 0;

-        r->call_timeout(paxos_protocol::decidereq, rpcc::to(1000), res, me, instance, v);
+        r->call_timeout(paxos_protocol::decidereq, milliseconds(100), res, me, instance, v);

     }
 }
 
     }
 }
 

@@ -203,17 +206,18 @@ void proposer_acceptor::commit(unsigned instance, const value_t & value) {
 }
 
 void proposer_acceptor::commit(unsigned instance, const value_t & value, lock & pxs_mutex_lock) {
 }
 
 void proposer_acceptor::commit(unsigned instance, const value_t & value, lock & pxs_mutex_lock) {

-    LOG("acceptor::commit: instance=" << instance << " has v=" << value);
+    LOG("instance=" << instance << " has v=" << value);

     if (instance > instance_h) {
     if (instance > instance_h) {

-        LOG("commit: highestacceptedinstance = " << instance);
+        LOG("highestacceptedinstance = " << instance);

         values[instance] = value;
         l.loginstance(instance, value);
         instance_h = instance;
         accepted = promise = {0, me};
         values[instance] = value;
         l.loginstance(instance, value);
         instance_h = instance;
         accepted = promise = {0, me};

-        accepted_value.clear();
+        string v = value; // gaaahhh aliasing of value and accepted_value
+        accepted_value.clear(); // this wipes out "value", too

         if (delegate) {
             pxs_mutex_lock.unlock();
         if (delegate) {
             pxs_mutex_lock.unlock();

-            delegate->paxos_commit(instance, value);
+            delegate->paxos_commit(instance, v);

             pxs_mutex_lock.lock();
         }
     }
             pxs_mutex_lock.lock();
         }
     }