osd/: add sync/async read methods to PGBackend

Signed-off-by: Samuel Just <sam.just@inktank.com>

src/osd/OSD.cc

@@ -185,6 +185,7 @@ OSDService::OSDService(OSD *osd) :
   scrub_finalize_wq(osd->scrub_finalize_wq),
   rep_scrub_wq(osd->rep_scrub_wq),
   push_wq("push_wq", cct->_conf->osd_recovery_thread_timeout, &osd->recovery_tp),
+  gen_wq("gen_wq", cct->_conf->osd_recovery_thread_timeout, &osd->recovery_tp),
   class_handler(osd->class_handler),
   publish_lock("OSDService::publish_lock"),
   pre_publish_lock("OSDService::pre_publish_lock"),

src/osd/OSD.h

@@ -312,6 +312,7 @@ public:
   ThreadPool::WorkQueue<PG> &scrub_finalize_wq;
   ThreadPool::WorkQueue<MOSDRepScrub> &rep_scrub_wq;
   GenContextWQ push_wq;
+  GenContextWQ gen_wq;
   ClassHandler  *&class_handler;
 
   void dequeue_pg(PG *pg, list<OpRequestRef> *dequeued);

src/osd/PGBackend.h

@@ -416,6 +416,19 @@
    virtual int objects_get_attrs(
      const hobject_t &hoid,
      map<string, bufferlist> *out) = 0;
+
+   virtual int objects_read_sync(
+     const hobject_t &hoid,
+     uint64_t off,
+     uint64_t len,
+     bufferlist *bl) = 0;
+
+   virtual void objects_read_async(
+     const hobject_t &hoid,
+     uint64_t off,
+     uint64_t len,
+     bufferlist *bl,
+     Context *on_complete) = 0;
  };
 
 #endif

src/osd/ReplicatedBackend.cc

@@ -324,6 +324,41 @@ int ReplicatedBackend::objects_get_attrs(
     *out);
 }
 
+int ReplicatedBackend::objects_read_sync(
+  const hobject_t &hoid,
+  uint64_t off,
+  uint64_t len,
+  bufferlist *bl)
+{
+  return osd->store->read(coll, hoid, off, len, *bl);
+}
+
+struct AsyncReadCallback : public GenContext<ThreadPool::TPHandle&> {
+  int r;
+  Context *c;
+  AsyncReadCallback(int r, Context *c) : r(r), c(c) {}
+  void finish(ThreadPool::TPHandle&) {
+    c->complete(r);
+    c = NULL;
+  }
+  ~AsyncReadCallback() {
+    delete c;
+  }
+};
+void ReplicatedBackend::objects_read_async(
+  const hobject_t &hoid,
+  uint64_t off,
+  uint64_t len,
+  bufferlist *bl,
+  Context *on_complete)
+{
+  int r = osd->store->read(coll, hoid, off, len, *bl);
+  osd->gen_wq.queue(
+    get_parent()->bless_gencontext(
+      new AsyncReadCallback(r, on_complete)));
+}
+
+
 class RPGTransaction : public PGBackend::PGTransaction {
   coll_t coll;
   coll_t temp_coll;

src/osd/ReplicatedBackend.h

@@ -176,6 +176,19 @@ public:
     const hobject_t &hoid,
     map<string, bufferlist> *out);
 
+  int objects_read_sync(
+    const hobject_t &hoid,
+    uint64_t off,
+    uint64_t len,
+    bufferlist *bl);
+
+  void objects_read_async(
+    const hobject_t &hoid,
+    uint64_t off,
+    uint64_t len,
+    bufferlist *bl,
+    Context *on_complete);
+
 private:
   // push
   struct PushInfo {