librbd: add sync point class

This class is to identify the check point of a customer request.

Signed-off-by: Peterson, Scott <scott.d.peterson@intel.com>
Signed-off-by: Li, Xiaoyan <xiaoyan.li@intel.com>
Signed-off-by: Lu, Yuan <yuan.y.lu@intel.com>
Signed-off-by: Chamarthy, Mahati <mahati.chamarthy@intel.com>

diff --git a/src/librbd/CMakeLists.txt b/src/librbd/CMakeLists.txt
index 693b15e7cef2cea785d2c498e8f01ed260d7ae9e..7d2870627f834ead1c482eedfb90960be02b1d54 100644 (file)
--- a/src/librbd/CMakeLists.txt
+++ b/src/librbd/CMakeLists.txt
@@ -165,6 +165,7 @@ if(WITH_RBD_RWL)
     ${librbd_internal_srcs}
     cache/rwl/ImageCacheState.cc
     cache/rwl/LogEntry.cc
+    cache/rwl/SyncPoint.cc
     cache/rwl/Types.cc
     cache/ReplicatedWriteLog.cc)
 endif()

diff --git a/src/librbd/cache/rwl/SyncPoint.cc b/src/librbd/cache/rwl/SyncPoint.cc
new file mode 100644 (file)
index 0000000..a135c6c
--- /dev/null
+++ b/src/librbd/cache/rwl/SyncPoint.cc
@@ -0,0 +1,51 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "SyncPoint.h"
+
+#define dout_subsys ceph_subsys_rbd
+#undef dout_prefix
+#define dout_prefix *_dout << "librbd::cache::rwl::SyncPoint: " << this << " " \
+                          <<  __func__ << ": "
+
+namespace librbd {
+namespace cache {
+namespace rwl {
+
+template <typename T>
+SyncPoint<T>::SyncPoint(T &rwl, const uint64_t sync_gen_num)
+  : rwl(rwl), log_entry(std::make_shared<SyncPointLogEntry>(sync_gen_num)) {
+  prior_log_entries_persisted = new C_Gather(rwl.m_image_ctx.cct, nullptr);
+  sync_point_persist = new C_Gather(rwl.m_image_ctx.cct, nullptr);
+  on_sync_point_appending.reserve(MAX_WRITES_PER_SYNC_POINT + 2);
+  on_sync_point_persisted.reserve(MAX_WRITES_PER_SYNC_POINT + 2);
+  if (RWL_VERBOSE_LOGGING) {
+    ldout(rwl.m_image_ctx.cct, 20) << "sync point " << sync_gen_num << dendl;
+  }
+}
+
+template <typename T>
+SyncPoint<T>::~SyncPoint() {
+  assert(on_sync_point_appending.empty());
+  assert(on_sync_point_persisted.empty());
+  assert(!earlier_sync_point);
+}
+
+template <typename T>
+std::ostream &SyncPoint<T>::format(std::ostream &os) const {
+  os << "log_entry=[" << *log_entry << "], "
+     << "earlier_sync_point=" << earlier_sync_point << ", "
+     << "later_sync_point=" << later_sync_point << ", "
+     << "final_op_sequence_num=" << final_op_sequence_num << ", "
+     << "prior_log_entries_persisted=" << prior_log_entries_persisted << ", "
+     << "prior_log_entries_persisted_complete=" << prior_log_entries_persisted_complete << ", "
+     << "append_scheduled=" << append_scheduled << ", "
+     << "appending=" << appending << ", "
+     << "on_sync_point_appending=" << on_sync_point_appending.size() << ", "
+     << "on_sync_point_persisted=" << on_sync_point_persisted.size() << "";
+  return os;
+};
+
+} // namespace rwl
+} // namespace cache
+} // namespace librbd

diff --git a/src/librbd/cache/rwl/SyncPoint.h b/src/librbd/cache/rwl/SyncPoint.h
new file mode 100644 (file)
index 0000000..7dad720
--- /dev/null
+++ b/src/librbd/cache/rwl/SyncPoint.h
@@ -0,0 +1,64 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#ifndef CEPH_LIBRBD_CACHE_RWL_SYNC_POINT_H
+#define CEPH_LIBRBD_CACHE_RWL_SYNC_POINT_H 
+
+#include "librbd/ImageCtx.h"
+#include "librbd/cache/rwl/LogEntry.h"
+#include "librbd/cache/rwl/Types.h"
+
+namespace librbd {
+namespace cache {
+namespace rwl {
+/* Limit work between sync points */
+static const uint64_t MAX_WRITES_PER_SYNC_POINT = 256;
+
+template <typename T>
+class SyncPoint {
+public:
+  T &rwl;
+  std::shared_ptr<SyncPointLogEntry> log_entry;
+  /* Use m_lock for earlier/later links */
+  std::shared_ptr<SyncPoint<T>> earlier_sync_point; /* NULL if earlier has completed */
+  std::shared_ptr<SyncPoint<T>> later_sync_point;
+  uint64_t final_op_sequence_num = 0;
+  /* A sync point can't appear in the log until all the writes bearing
+   * it and all the prior sync points have been appended and
+   * persisted.
+   *
+   * Writes bearing this sync gen number and the prior sync point will be
+   * sub-ops of this Gather. This sync point will not be appended until all
+   * these complete to the point where their persist order is guaranteed. */
+  C_Gather *prior_log_entries_persisted;
+  int prior_log_entries_persisted_result = 0;
+  int prior_log_entries_persisted_complete = false;
+  /* The finisher for this will append the sync point to the log.  The finisher
+   * for m_prior_log_entries_persisted will be a sub-op of this. */
+  C_Gather *sync_point_persist;
+  bool append_scheduled = false;
+  bool appending = false;
+  /* Signal these when this sync point is appending to the log, and its order
+   * of appearance is guaranteed. One of these is is a sub-operation of the
+   * next sync point's m_prior_log_entries_persisted Gather. */
+  std::vector<Context*> on_sync_point_appending;
+  /* Signal these when this sync point is appended and persisted. User
+   * aio_flush() calls are added to this. */
+  std::vector<Context*> on_sync_point_persisted;
+
+  SyncPoint(T &rwl, const uint64_t sync_gen_num);
+  ~SyncPoint();
+  SyncPoint(const SyncPoint&) = delete;
+  SyncPoint &operator=(const SyncPoint&) = delete;
+  std::ostream &format(std::ostream &os) const;
+  friend std::ostream &operator<<(std::ostream &os,
+                                  const SyncPoint &p) {
+    return p.format(os);
+  }
+};
+
+} // namespace rwl
+} // namespace cache
+} // namespace librbd
+
+#endif // CEPH_LIBRBD_CACHE_RWL_SYNC_POINT_H

diff --git a/src/librbd/cache/rwl/Types.h b/src/librbd/cache/rwl/Types.h
index b134beda05e71e126129e7db52f2d1d61131d437..b02b2fdda36d867284120de92e1473ac055f92b5 100644 (file)
--- a/src/librbd/cache/rwl/Types.h
+++ b/src/librbd/cache/rwl/Types.h
@@ -140,6 +140,8 @@ namespace librbd {
 namespace cache {
 namespace rwl {
 
+static const bool RWL_VERBOSE_LOGGING = false;
+
 /* Defer a set of Contexts until destruct/exit. Used for deferring
  * work on a given thread until a required lock is dropped. */
 class DeferredContexts {