[trafficserver] branch master updated: Optimize: If failed on migrateToCurrentThread, put the server session back to global server session pool

[ok...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

oknet pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/trafficserver.git


The following commit(s) were added to refs/heads/master by this push:
     new c776c66  Optimize: If failed on migrateToCurrentThread, put the server session back to global server session pool
c776c66 is described below

commit c776c6677b0c005dd511945ae023a14f8f6b0bc3
Author: Oknet Xu <xu...@skyguard.com.cn>
AuthorDate: Fri Sep 1 22:18:54 2017 +0800

    Optimize: If failed on migrateToCurrentThread, put the server session back to global server session pool
---
 iocore/net/UnixNetVConnection.cc | 74 +++++++++++++++++++++++++++-------------
 proxy/http/HttpSessionManager.cc | 24 ++++++-------
 2 files changed, 61 insertions(+), 37 deletions(-)

diff --git a/iocore/net/UnixNetVConnection.cc b/iocore/net/UnixNetVConnection.cc
index a4c7769..0e97ffa 100644
--- a/iocore/net/UnixNetVConnection.cc
+++ b/iocore/net/UnixNetVConnection.cc
@@ -1244,6 +1244,7 @@ UnixNetVConnection::populate(Connection &con_in, Continuation *c, void *arg)
   }
 
   if (h->startIO(this) < 0) {
+    con_in.move(this->con);
     Debug("iocore_net", "populate : Failed to add to epoll list");
     return EVENT_ERROR;
   }
@@ -1430,44 +1431,71 @@ UnixNetVConnection::migrateToCurrentThread(Continuation *cont, EThread *t)
     return this;
   }
 
-  Connection hold_con;
-  hold_con.move(this->con);
-  SSLNetVConnection *sslvc = dynamic_cast<SSLNetVConnection *>(this);
-
-  SSL *save_ssl = (sslvc) ? sslvc->ssl : nullptr;
-  if (save_ssl) {
-    SSLNetVCDetach(sslvc->ssl);
-    sslvc->ssl = nullptr;
+  // Lock the NetHandler first in order to put the new NetVC into NetHandler and InactivityCop.
+  // It is safe and no performance issue to get the mutex lock for a NetHandler of current ethread.
+  SCOPED_MUTEX_LOCK(lock, client_nh->mutex, t);
+
+  // Try to get the mutex lock for NetHandler of this NetVC
+  MUTEX_TRY_LOCK(lock_src, this->nh->mutex, t);
+  if (lock_src.is_locked()) {
+    // Deattach this NetVC from original NetHandler & InactivityCop.
+    this->nh->stopCop(this);
+    this->nh->stopIO(this);
+    // Put this NetVC into current NetHandler & InactivityCop.
+    this->thread = t;
+    client_nh->startIO(this);
+    client_nh->startCop(this);
+    // Move this NetVC to current EThread Successfully.
+    return this;
   }
 
-  // Do_io_close will signal the VC to be freed on the original thread
-  // Since we moved the con context, the fd will not be closed
-  // Go ahead and remove the fd from the original thread's epoll structure, so it is not
-  // processed on two threads simultaneously
-  this->ep.stop();
-  this->do_io_close();
+  // Failed to get the mutex lock for original NetHandler.
+  // Try to migrate it by create a new NetVC and then move con.fd and ssl ctx.
+  SSLNetVConnection *sslvc = dynamic_cast<SSLNetVConnection *>(this);
+  SSL *save_ssl            = (sslvc) ? sslvc->ssl : nullptr;
+
+  UnixNetVConnection *ret_vc = nullptr;
 
   // Create new VC:
   if (save_ssl) {
     SSLNetVConnection *sslvc = static_cast<SSLNetVConnection *>(sslNetProcessor.allocate_vc(t));
-    if (sslvc->populate(hold_con, cont, save_ssl) != EVENT_DONE) {
-      sslvc->do_io_close();
-      sslvc = nullptr;
+    if (sslvc->populate(this->con, cont, save_ssl) != EVENT_DONE) {
+      sslvc->free(t);
+      sslvc  = nullptr;
+      ret_vc = this;
     } else {
       sslvc->set_context(get_context());
+      ret_vc = dynamic_cast<UnixNetVConnection *>(sslvc);
     }
-    return sslvc;
-    // Update the SSL fields
   } else {
     UnixNetVConnection *netvc = static_cast<UnixNetVConnection *>(netProcessor.allocate_vc(t));
-    if (netvc->populate(hold_con, cont, save_ssl) != EVENT_DONE) {
-      netvc->do_io_close();
-      netvc = nullptr;
+    if (netvc->populate(this->con, cont, save_ssl) != EVENT_DONE) {
+      netvc->free(t);
+      netvc  = nullptr;
+      ret_vc = this;
     } else {
       netvc->set_context(get_context());
+      ret_vc = netvc;
     }
-    return netvc;
   }
+
+  // clear con.fd and ssl ctx from this NetVC since a new NetVC is created.
+  if (ret_vc != this) {
+    if (save_ssl) {
+      SSLNetVCDetach(sslvc->ssl);
+      sslvc->ssl = nullptr;
+    }
+    ink_assert(this->con.fd == NO_FD);
+
+    // Do_io_close will signal the VC to be freed on the original thread
+    // Since we moved the con context, the fd will not be closed
+    // Go ahead and remove the fd from the original thread's epoll structure, so it is not
+    // processed on two threads simultaneously
+    this->ep.stop();
+    this->do_io_close();
+  }
+
+  return ret_vc;
 }
 
 void
diff --git a/proxy/http/HttpSessionManager.cc b/proxy/http/HttpSessionManager.cc
index 1e4334a..49450f2 100644
--- a/proxy/http/HttpSessionManager.cc
+++ b/proxy/http/HttpSessionManager.cc
@@ -326,21 +326,17 @@ HttpSessionManager::acquire_session(Continuation * /* cont ATS_UNUSED */, sockad
           UnixNetVConnection *server_vc = dynamic_cast<UnixNetVConnection *>(to_return->get_netvc());
           if (server_vc) {
             UnixNetVConnection *new_vc = server_vc->migrateToCurrentThread(sm, ethread);
-            // The VC moved, free up the original one
-            if (new_vc != server_vc) {
-              ink_assert(new_vc == nullptr || new_vc->nh != nullptr);
-              if (!new_vc) {
-                // Close out to_return, we were't able to get a connection
-                to_return->do_io_close();
-                to_return = nullptr;
-                retval    = HSM_NOT_FOUND;
-              } else {
-                // Keep things from timing out on us
-                new_vc->set_inactivity_timeout(new_vc->get_inactivity_timeout());
-                to_return->set_netvc(new_vc);
-              }
+            if (new_vc->thread != ethread) {
+              // Failed to migrate, put it back to global session pool
+              m_g_pool->releaseSession(to_return);
+              to_return = nullptr;
+              retval    = HSM_NOT_FOUND;
+            } else if (new_vc != server_vc) {
+              // The VC migrated, keep things from timing out on us
+              new_vc->set_inactivity_timeout(new_vc->get_inactivity_timeout());
+              to_return->set_netvc(new_vc);
             } else {
-              // Keep things from timing out on us
+              // The VC moved, keep things from timing out on us
               server_vc->set_inactivity_timeout(server_vc->get_inactivity_timeout());
             }
           }

-- 
To stop receiving notification emails like this one, please contact
['"commits@trafficserver.apache.org" <co...@trafficserver.apache.org>'].