[folks] Prevent extra "concurrent" PersonaStore.prepare() calls from one thread.

[Jeremy Whiting <jpwhiting src gnome org>]

commit d94b174d002d9304fff090c4eca8d1aa2930d6c6
Author: Travis Reitter <travis reitter collabora co uk>
Date:   Wed Jul 6 14:48:43 2011 -0700

    Prevent extra "concurrent" PersonaStore.prepare() calls from one thread.
    
    The lock() calls which were in place only prevent concurrent calls from
    different threads; however, the critical section could still be reached
    from two async calls in the same thread a la:
    
    backend.prepare.begin ((s,r) => {...});
    backend.prepare.begin ((s,r) => {...});
    
    The bodies of the handlers would not literally execute concurrently, but
    would be interleaved if each were sufficiently long. Our fix simply
    ignores any calls which happen while one is still working.
    
    (yield backend.prepare(); yield backend.prepare(); was already safe, of
    course)
    
    Helps: bgo#652637 - Don't hold locks across async calls

 backends/key-file/kf-persona-store.vala       |    4 ++++
 backends/telepathy/lib/tpf-persona-store.vala |    1 +
 backends/tracker/lib/trf-persona-store.vala   |    4 ++++
 3 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/backends/key-file/kf-persona-store.vala b/backends/key-file/kf-persona-store.vala
index a5905a0..2c06e0d 100644
--- a/backends/key-file/kf-persona-store.vala
+++ b/backends/key-file/kf-persona-store.vala
@@ -235,6 +235,7 @@ public class Folks.Backends.Kf.PersonaStore : Folks.PersonaStore
                               _("The relationship key file '%s' could not be loaded: %s"),
                               filename, e1.message);
                           this.removed ();
+                          this._prepare_pending = false;
                           return;
                         }
                     }
@@ -257,6 +258,7 @@ public class Folks.Backends.Kf.PersonaStore : Folks.PersonaStore
                               _("The relationship key file directory '%s' could not be created: %s"),
                               parent_dir.get_path (), e3.message);
                           this.removed ();
+                          this._prepare_pending = false;
                           return;
                         }
                     }
@@ -281,6 +283,7 @@ public class Folks.Backends.Kf.PersonaStore : Folks.PersonaStore
                               _("The relationship key file '%s' could not be created: %s"),
                               filename, e2.message);
                           this.removed ();
+                          this._prepare_pending = false;
                           return;
                         }
                     }
@@ -306,6 +309,7 @@ public class Folks.Backends.Kf.PersonaStore : Folks.PersonaStore
                 }
 
               this._is_prepared = true;
+              this._prepare_pending = false;
               this.notify_property ("is-prepared");
 
               /* We've finished loading all the personas we know about */
diff --git a/backends/telepathy/lib/tpf-persona-store.vala b/backends/telepathy/lib/tpf-persona-store.vala
index c7eff9b..8afe084 100644
--- a/backends/telepathy/lib/tpf-persona-store.vala
+++ b/backends/telepathy/lib/tpf-persona-store.vala
@@ -565,6 +565,7 @@ public class Tpf.PersonaStore : Folks.PersonaStore
                   "(ID: %s)", this.id);
 
               this._is_prepared = true;
+              this._prepare_pending = false;
               this.notify_property ("is-prepared");
             }
           finally
diff --git a/backends/tracker/lib/trf-persona-store.vala b/backends/tracker/lib/trf-persona-store.vala
index f442e8d..c53202f 100644
--- a/backends/tracker/lib/trf-persona-store.vala
+++ b/backends/tracker/lib/trf-persona-store.vala
@@ -1144,6 +1144,10 @@ public class Trf.PersonaStore : Folks.PersonaStore
                   this.removed ();
                   throw new PersonaStoreError.INVALID_ARGUMENT (e3.message);
                 }
+              finally
+                {
+                  this._prepare_pending = false;
+                }
             }
           finally
             {