librados: add get_pg_hash_position to determine pg while listing objects

Signed-off-by: Sage Weil <sage@inktank.com>

5 files changed, 65 insertions, 0 deletions

diff --git a/src/include/rados/librados.h b/src/include/rados/librados.h
index 515663c2335..449aeebe41a 100644
--- a/src/include/rados/librados.h
+++ b/src/include/rados/librados.h
@@ -685,6 +685,14 @@ void rados_ioctx_set_namespace(rados_ioctx_t io, const char *nspace);
 int rados_objects_list_open(rados_ioctx_t io, rados_list_ctx_t *ctx);
 
 /**
+ * Return hash position of iterator, rounded to the current PG
+ *
+ * @param ctx iterator marking where you are in the listing
+ * @returns current hash position, rounded to the current pg
+ */
+uint32_t rados_objects_list_get_pg_hash_position(rados_list_ctx_t ctx);
+
+/**
  * Get the next object name and locator in the pool
  *
  * *entry and *key are valid until next call to rados_objects_list_*
diff --git a/src/include/rados/librados.hpp b/src/include/rados/librados.hpp
index 3f6d025ff41..46cedd578c5 100644
--- a/src/include/rados/librados.hpp
+++ b/src/include/rados/librados.hpp
@@ -71,6 +71,10 @@ namespace librados
     ObjectIterator &operator++(); // Preincrement
     ObjectIterator operator++(int); // Postincrement
     friend class IoCtx;
+
+    /// get current hash position of the iterator, rounded to the current pg
+    uint32_t get_pg_hash_position() const;
+
   private:
     void get_next();
     std::tr1::shared_ptr < ObjListCtx > ctx;
diff --git a/src/librados/librados.cc b/src/librados/librados.cc
index 217a0a7bfb2..a916abcff26 100644
--- a/src/librados/librados.cc
+++ b/src/librados/librados.cc
@@ -506,6 +506,11 @@ void librados::ObjectIterator::get_next()
   cur_obj = make_pair(entry, key ? key : string());
 }
 
+uint32_t librados::ObjectIterator::get_pg_hash_position() const
+{
+  return ctx->lc->get_pg_hash_position();
+}
+
 const librados::ObjectIterator librados::ObjectIterator::__EndObjectIterator(NULL);
 
 ///////////////////////////// PoolAsyncCompletion //////////////////////////////
@@ -2529,6 +2534,13 @@ extern "C" void rados_objects_list_close(rados_list_ctx_t h)
   delete lh;
 }
 
+extern "C" uint32_t rados_objects_list_get_pg_hash_position(
+  rados_list_ctx_t listctx)
+{
+  librados::ObjListCtx *lh = (librados::ObjListCtx *)listctx;
+  return lh->lc->get_pg_hash_position();
+}
+
 extern "C" int rados_objects_list_next(rados_list_ctx_t listctx, const char **entry, const char **key)
 {
   librados::ObjListCtx *lh = (librados::ObjListCtx *)listctx;
diff --git a/src/osdc/Objecter.h b/src/osdc/Objecter.h
index b42a211b754..ca67aff3660 100644
--- a/src/osdc/Objecter.h
+++ b/src/osdc/Objecter.h
@@ -1031,6 +1031,10 @@ public:
     ListContext() : current_pg(0), current_pg_epoch(0), starting_pg_num(0),
 		    at_end(false), pool_id(0),
 		    pool_snap_seq(0), max_entries(0) {}
+
+    uint32_t get_pg_hash_position() const {
+      return current_pg;
+    }
   };
 
   struct C_List : public Context {
diff --git a/src/test/librados/list.cc b/src/test/librados/list.cc
index 1ea56c295a4..fca0ad40395 100644
--- a/src/test/librados/list.cc
+++ b/src/test/librados/list.cc
@@ -1,5 +1,6 @@
 #include "include/rados/librados.h"
 #include "include/rados/librados.hpp"
+#include "include/stringify.h"
 #include "test/librados/test.h"
 
 #include "gtest/gtest.h"
@@ -177,3 +178,39 @@ TEST(LibRadosList, ListObjectsPPNS) {
   ioctx.close();
   ASSERT_EQ(0, destroy_one_pool_pp(pool_name, cluster));
 }
+
+TEST(LibRadosList, ListObjectsManyPP) {
+  std::string pool_name = get_temp_pool_name();
+  Rados cluster;
+  ASSERT_EQ("", create_one_pool_pp(pool_name, cluster));
+  IoCtx ioctx;
+  cluster.ioctx_create(pool_name.c_str(), ioctx);
+
+  char buf[128];
+  memset(buf, 0xcc, sizeof(buf));
+  bufferlist bl;
+  bl.append(buf, sizeof(buf));
+
+  for (int i=0; i<256; ++i) {
+    ASSERT_EQ((int)sizeof(buf), ioctx.write(stringify(i), bl, bl.length(), 0));
+  }
+
+  librados::ObjectIterator it = ioctx.objects_begin();
+  std::set<std::string> saw_obj;
+  std::set<int> saw_pg;
+  for (; it != ioctx.objects_end(); ++it) {
+    std::cout << it->first
+	      << " " << it.get_pg_hash_position() << std::endl;
+    saw_obj.insert(it->first);
+    saw_pg.insert(it.get_pg_hash_position());
+  }
+  std::cout << "saw " << saw_pg.size() << " pgs " << std::endl;
+
+  // make sure they are 0..n
+  for (unsigned i = 0; i < saw_pg.size(); ++i)
+    ASSERT_TRUE(saw_pg.count(i));
+
+  ioctx.close();
+  ASSERT_EQ(0, destroy_one_pool_pp(pool_name, cluster));
+}
+