X-Git-Url: http://xvm.mit.edu/gitweb/invirt/third/libt4.git/blobdiff_plain/869c0cc91d8f6b2bb80026616372d16450b64d9f..e0c49ff6ba44cf5b47ab91d58b67763f5a1c7a58:/paxos.cc

diff --git a/paxos.cc b/paxos.cc
index 2c7e79a..c7f2d1d 100644
--- a/paxos.cc
+++ b/paxos.cc
@@ -93,20 +93,20 @@ bool proposer_acceptor::prepare(unsigned instance, nodes_t & accepts,
     prepareres res;
     prop_t highest_n_a{0, ""};
     for (auto i : nodes) {
-        auto r = rpcc::bind_cached(i);
-        if (!r)
+        auto cl = rpcc::bind_cached(i);
+        if (!cl)
             continue;
-        auto status = (paxos_protocol::status)r->call_timeout(
-                paxos_protocol::preparereq, milliseconds(100), res, me, instance, proposal);
+        int status = cl->call_timeout(paxos_protocol::preparereq, milliseconds(100),
+                res, me, instance, proposal);
         if (status == paxos_protocol::OK) {
-            if (res.oldinstance) {
+            LOG << "preparereq response type=" << res.type << " n_a=(" << res.n_a.n
+                << ", " << res.n_a.m << ") " << "v_a=\"" << res.v_a << "\"";
+            if (res.type == prepareres::oldinstance) {
                 LOG << "commiting old instance!";
-                commit(instance, res.v_a);
+                lock ml(acceptor_mutex);
+                commit(instance, res.v_a, ml);
                 return false;
-            }
-            LOG << "preparereq responded with oldinstance=" << res.oldinstance << " accept=" << res.accept << " n_a=(" << res.n_a.n << ", " << res.n_a.m << ") "
-                << "v_a=\"" << res.v_a << "\"";
-            if (res.accept) {
+            } else if (res.type == prepareres::accept) {
                 accepts.push_back(i);
                 if (res.n_a >= highest_n_a) {
                     LOG << "found a newer accepted proposal, \"" << res.v_a << "\", with number (" << res.n_a.n << ", " << res.n_a.m << ")";
@@ -121,50 +121,42 @@ bool proposer_acceptor::prepare(unsigned instance, nodes_t & accepts,
 
 void proposer_acceptor::accept(unsigned instance, nodes_t & accepts,
         const nodes_t & nodes, const value_t & v) {
+    bool accept = false;
     for (auto i : nodes) {
-        auto r = rpcc::bind_cached(i);
-        if (!r)
-            continue;
-        bool accept = false;
-        int status = r->call_timeout(
-                paxos_protocol::acceptreq, milliseconds(100), accept, me, instance, proposal, v);
-        if (status == paxos_protocol::OK && accept)
-            accepts.push_back(i);
+        if (auto cl = rpcc::bind_cached(i)) {
+            int status = cl->call_timeout(paxos_protocol::acceptreq, milliseconds(100),
+                    accept, me, instance, proposal, v);
+            if (status == paxos_protocol::OK && accept)
+                accepts.push_back(i);
+        }
     }
 }
 
 void proposer_acceptor::decide(unsigned instance, const nodes_t & accepts, const value_t & v) {
-    for (auto i : accepts) {
-        auto r = rpcc::bind_cached(i);
-        if (!r)
-            continue;
-        int res = 0;
-        r->call_timeout(paxos_protocol::decidereq, milliseconds(100), res, me, instance, v);
-    }
+    int res = 0;
+    for (auto i : accepts)
+        if (auto cl = rpcc::bind_cached(i))
+            cl->call_timeout(paxos_protocol::decidereq, milliseconds(100), res, me, instance, v);
 }
 
 paxos_protocol::status
 proposer_acceptor::preparereq(prepareres & r, const node_t &, unsigned instance, prop_t n) {
     LOG << "instance " << instance << " proposal (" << n.n << ", " << n.m << ")";
     lock ml(acceptor_mutex);
-    r.oldinstance = false;
-    r.accept = false;
-    r.n_a = accepted;
-    r.v_a = accepted_value;
     if (instance <= instance_h) {
         LOG << "old instance " << instance << " has value " << values[instance];
-        r.oldinstance = true;
-        r.v_a = values[instance];
+        r = prepareres{prepareres::oldinstance, accepted, values[instance]};
     } else if (n > promise) {
         LOG << "looks good to me";
         promise = n;
         l.logprop(promise);
-        r.accept = true;
+        r = prepareres{prepareres::accept, accepted, accepted_value};
     } else {
         LOG << "I totally rejected this request.  Ha.";
+        r = prepareres{prepareres::reject, accepted, accepted_value};
     }
-    LOG << "preparereq is responding with oldinstance=" << r.oldinstance << " accept=" << r.accept << " n_a=(" << r.n_a.n << ", " << r.n_a.m << ") "
-        << "v_a=\"" << r.v_a << "\"";
+    LOG << "preparereq is responding with oldinstance=" << r.oldinstance << " accept=" << r.accept
+        << " n_a=(" << r.n_a.n << ", " << r.n_a.m << ") " << "v_a=\"" << r.v_a << "\"";
     return paxos_protocol::OK;
 }
 
@@ -172,17 +164,15 @@ paxos_protocol::status
 proposer_acceptor::acceptreq(bool & r, const node_t &, unsigned instance, prop_t n, const value_t & v) {
     lock ml(acceptor_mutex);
     r = false;
-    if (instance == instance_h + 1) {
-        if (n >= promise) {
-            accepted = n;
-            accepted_value = v;
-            l.logaccept(accepted, accepted_value);
-            r = true;
-        }
-        return paxos_protocol::OK;
-    } else {
+    if (instance != instance_h + 1)
         return paxos_protocol::ERR;
+    if (n >= promise) {
+        accepted = n;
+        accepted_value = v;
+        l.logaccept(accepted, accepted_value);
+        r = true;
     }
+    return paxos_protocol::OK;
 }
 
 paxos_protocol::status
@@ -191,7 +181,7 @@ proposer_acceptor::decidereq(int &, const node_t &, unsigned instance, const val
     LOG << "decidereq for accepted instance " << instance << " (my instance " << instance_h << ") v=" << accepted_value;
     if (instance == instance_h + 1) {
         VERIFY(accepted_value == v);
-        commit(instance, accepted_value, ml);
+        commit(instance, v, ml);
     } else if (instance <= instance_h) {
         // we are ahead; ignore.
     } else {
@@ -201,12 +191,9 @@ proposer_acceptor::decidereq(int &, const node_t &, unsigned instance, const val
     return paxos_protocol::OK;
 }
 
-void proposer_acceptor::commit(unsigned instance, const value_t & value) {
-    lock ml(acceptor_mutex);
-    commit(instance, value, ml);
-}
-
-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 & acceptor_mutex_lock) {
+    VERIFY(&value != &accepted_value); // eited by aliasing?
+    VERIFY(acceptor_mutex_lock);
     LOG << "instance=" << instance << " has v=" << value;
     if (instance > instance_h) {
         LOG << "highestacceptedinstance = " << instance;
@@ -214,12 +201,11 @@ void proposer_acceptor::commit(unsigned instance, const value_t & value, lock &
         l.loginstance(instance, value);
         instance_h = instance;
         accepted = promise = {0, me};
-        string v = value; // gaaahhh aliasing of value and accepted_value
-        accepted_value.clear(); // this wipes out "value", too
+        accepted_value.clear();
         if (delegate) {
-            pxs_mutex_lock.unlock();
-            delegate->paxos_commit(instance, v);
-            pxs_mutex_lock.lock();
+            acceptor_mutex_lock.unlock();
+            delegate->paxos_commit(instance, value);
+            acceptor_mutex_lock.lock();
         }
     }
 }