X-Git-Url: http://xvm.mit.edu/gitweb/invirt/third/libt4.git/blobdiff_plain/5a5c578e2e358a121cdb9234a6cb11c4ecfbf323..b2609562b3d4fc548afcc0a3dfe4ff5fd4ae3d36:/paxos.cc

diff --git a/paxos.cc b/paxos.cc
index 095d56a..8b00ad8 100644
--- a/paxos.cc
+++ b/paxos.cc
@@ -1,12 +1,6 @@
 #include "paxos.h"
 #include "handle.h"
 
-string print_members(const nodes_t &nodes) {
-    ostringstream ost;
-    copy(nodes.begin(), nodes.end(), ostream_iterator<string>(ost, ", "));
-    return ost.str();
-}
-
 bool isamember(const node_t & m, const nodes_t & nodes) {
     return find(nodes.begin(), nodes.end(), m) != nodes.end();
 }
@@ -26,7 +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.
 
-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)
 {
@@ -45,20 +39,23 @@ proposer_acceptor::proposer_acceptor(class paxos_change *_delegate,
 bool proposer_acceptor::run(unsigned instance, const nodes_t & cur_nodes, const value_t & newv)
 {
     lock ml(proposer_mutex);
-    LOG("start: initiate paxos for " << print_members(cur_nodes) << " w. i=" << instance << " v=" << newv << " stable=" << stable);
+    LOG("initiate paxos for " << cur_nodes << " w. i=" << instance << " v=\"" << newv << "\" stable=" << stable);
     if (!stable) {  // already running proposer?
-        LOG("proposer::run: already running");
+        LOG("paxos proposer already running");
         return false;
     }
     stable = false;
     bool r = false;
-    my_n.n = std::max(n_h.n, my_n.n) + 1;
+    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("paxos::run: received a majority of prepare responses");
+            LOG("received a majority of prepare responses");
+
+            if (!v.size())
+                v = newv;
 
             breakpoint1();
 
@@ -67,20 +64,20 @@ bool proposer_acceptor::run(unsigned instance, const nodes_t & cur_nodes, const
             accept(instance, accepts, nodes, v);
 
             if (majority(cur_nodes, accepts)) {
-                LOG("paxos::run: received a majority of accept responses");
+                LOG("received a majority of accept responses");
 
                 breakpoint2();
 
                 decide(instance, accepts, v);
                 r = true;
             } else {
-                LOG("paxos::run: no majority of accept responses");
+                LOG("no majority of accept responses");
             }
         } else {
-            LOG("paxos::run: no majority of prepare responses");
+            LOG("no majority of prepare responses");
         }
     } else {
-        LOG("paxos::run: prepare is rejected " << stable);
+        LOG("prepare is rejected " << stable);
     }
     stable = true;
     return r;
@@ -88,6 +85,7 @@ bool proposer_acceptor::run(unsigned instance, const nodes_t & cur_nodes, const
 
 bool proposer_acceptor::prepare(unsigned instance, nodes_t & accepts,
         const nodes_t & nodes, value_t & v) {
+    LOG("sending prepare messages (" << proposal.n << ", " << proposal.m << ", \"" << v << "\")");
     prepareres res;
     prop_t highest_n_a{0, ""};
     for (auto i : nodes) {
@@ -96,17 +94,19 @@ bool proposer_acceptor::prepare(unsigned instance, nodes_t & accepts,
         if (!r)
             continue;
         auto status = (paxos_protocol::status)r->call_timeout(
-                paxos_protocol::preparereq, rpcc::to(1000), res, me, instance, my_n);
+                paxos_protocol::preparereq, milliseconds(100), res, me, instance, proposal);
         if (status == paxos_protocol::OK) {
             if (res.oldinstance) {
                 LOG("commiting old instance!");
                 commit(instance, res.v_a);
                 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) {
                 accepts.push_back(i);
                 if (res.n_a >= highest_n_a) {
-                    LOG("found a newer accepted proposal");
+                    LOG("found a newer accepted proposal, \"" << res.v_a << "\", with number (" << res.n_a.n << ", " << res.n_a.m << ")");
                     v = res.v_a;
                     highest_n_a = res.n_a;
                 }
@@ -125,7 +125,7 @@ void proposer_acceptor::accept(unsigned instance, nodes_t & accepts,
             continue;
         bool accept = false;
         int status = r->call_timeout(
-                paxos_protocol::acceptreq, rpcc::to(1000), accept, me, instance, my_n, v);
+                paxos_protocol::acceptreq, milliseconds(100), accept, me, instance, proposal, v);
         if (status == paxos_protocol::OK && accept)
             accepts.push_back(i);
     }
@@ -138,27 +138,32 @@ void proposer_acceptor::decide(unsigned instance, const nodes_t & accepts, const
         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);
     }
 }
 
 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 = n_a;
-    r.v_a = v_a;
+    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];
-    } else if (n > n_h) {
-        n_h = n;
-        l.logprop(n_h);
+    } else if (n > promise) {
+        LOG("looks good to me");
+        promise = n;
+        l.logprop(promise);
         r.accept = true;
     } else {
         LOG("I totally rejected this request.  Ha.");
     }
+    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;
 }
 
@@ -167,10 +172,10 @@ proposer_acceptor::acceptreq(bool & r, const node_t &, unsigned instance, prop_t
     lock ml(acceptor_mutex);
     r = false;
     if (instance == instance_h + 1) {
-        if (n >= n_h) {
-            n_a = n;
-            v_a = v;
-            l.logaccept(n_a, v_a);
+        if (n >= promise) {
+            accepted = n;
+            accepted_value = v;
+            l.logaccept(accepted, accepted_value);
             r = true;
         }
         return paxos_protocol::OK;
@@ -182,10 +187,10 @@ proposer_acceptor::acceptreq(bool & r, const node_t &, unsigned instance, prop_t
 paxos_protocol::status
 proposer_acceptor::decidereq(int &, const node_t &, unsigned instance, const value_t & v) {
     lock ml(acceptor_mutex);
-    LOG("decidereq for accepted instance " << instance << " (my instance " << instance_h << ") v=" << v_a);
+    LOG("decidereq for accepted instance " << instance << " (my instance " << instance_h << ") v=" << accepted_value);
     if (instance == instance_h + 1) {
-        VERIFY(v_a == v);
-        commit(instance, v_a, ml);
+        VERIFY(accepted_value == v);
+        commit(instance, accepted_value, ml);
     } else if (instance <= instance_h) {
         // we are ahead; ignore.
     } else {
@@ -201,17 +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) {
-    LOG("acceptor::commit: instance=" << instance << " has v=" << value);
+    LOG("instance=" << instance << " has v=" << value);
     if (instance > instance_h) {
-        LOG("commit: highestacceptedinstance = " << instance);
+        LOG("highestacceptedinstance = " << instance);
         values[instance] = value;
         l.loginstance(instance, value);
         instance_h = instance;
-        n_a = n_h = {0, me};
-        v_a.clear();
+        accepted = promise = {0, me};
+        string v = value; // gaaahhh aliasing of value and accepted_value
+        accepted_value.clear(); // this wipes out "value", too
         if (delegate) {
             pxs_mutex_lock.unlock();
-            delegate->paxos_commit(instance, value);
+            delegate->paxos_commit(instance, v);
             pxs_mutex_lock.lock();
         }
     }