1 files changed, 190 insertions, 0 deletions
diff --git a/src/osd/object_state.h b/src/osd/object_state.h
new file mode 100644
index 000000000..31987d2a4
--- /dev/null
+++ b/src/osd/object_state.h
@@ -0,0 +1,190 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#pragma once
+
+#include "osd_types.h"
+
+struct ObjectState {
+  object_info_t oi;
+  bool exists;         ///< the stored object exists (i.e., we will remember the object_info_t)
+
+  ObjectState() : exists(false) {}
+
+  ObjectState(const object_info_t &oi_, bool exists_)
+    : oi(oi_), exists(exists_) {}
+  ObjectState(object_info_t &&oi_, bool exists_)
+    : oi(std::move(oi_)), exists(exists_) {}
+  ObjectState(const hobject_t &obj) : oi(obj), exists(false) {}
+};
+
+struct RWState {
+  enum State {
+    RWNONE,
+    RWREAD,
+    RWWRITE,
+    RWEXCL,
+  };
+  static const char *get_state_name(State s) {
+    switch (s) {
+    case RWNONE: return "none";
+    case RWREAD: return "read";
+    case RWWRITE: return "write";
+    case RWEXCL: return "excl";
+    default: return "???";
+    }
+  }
+  const char *get_state_name() const {
+    return get_state_name(state);
+  }
+
+  int count;              ///< number of readers or writers
+  int waiters = 0;        ///< number waiting
+
+  State state:4;               ///< rw state
+  /// if set, restart backfill when we can get a read lock
+  bool recovery_read_marker:1;
+  /// if set, requeue snaptrim on lock release
+  bool snaptrimmer_write_marker:1;
+
+  RWState()
+    : count(0),
+      state(RWNONE),
+      recovery_read_marker(false),
+      snaptrimmer_write_marker(false)
+  {}
+
+  /// this function adjusts the counts if necessary
+  bool get_read_lock() {
+    // don't starve anybody!
+    if (waiters > 0) {
+      return false;
+    }
+    switch (state) {
+    case RWNONE:
+      ceph_assert(count == 0);
+      state = RWREAD;
+      // fall through
+    case RWREAD:
+      count++;
+      return true;
+    case RWWRITE:
+      return false;
+    case RWEXCL:
+      return false;
+    default:
+      ceph_abort_msg("unhandled case");
+      return false;
+    }
+  }
+
+  bool get_write_lock(bool greedy=false) {
+    if (!greedy) {
+      // don't starve anybody!
+      if (waiters > 0 ||
+	  recovery_read_marker) {
+	return false;
+      }
+    }
+    switch (state) {
+    case RWNONE:
+      ceph_assert(count == 0);
+      state = RWWRITE;
+      // fall through
+    case RWWRITE:
+      count++;
+      return true;
+    case RWREAD:
+      return false;
+    case RWEXCL:
+      return false;
+    default:
+      ceph_abort_msg("unhandled case");
+      return false;
+    }
+  }
+  bool get_excl_lock() {
+    switch (state) {
+    case RWNONE:
+      ceph_assert(count == 0);
+      state = RWEXCL;
+      count = 1;
+      return true;
+    case RWWRITE:
+      return false;
+    case RWREAD:
+      return false;
+    case RWEXCL:
+      return false;
+    default:
+      ceph_abort_msg("unhandled case");
+      return false;
+    }
+  }
+  /// same as get_write_lock, but ignore starvation
+  bool take_write_lock() {
+    if (state == RWWRITE) {
+      count++;
+      return true;
+    }
+    return get_write_lock();
+  }
+  bool dec() {
+    ceph_assert(count > 0);
+    count--;
+    if (count == 0) {
+      state = RWNONE;
+      return true;
+    } else {
+      return false;
+    }
+  }
+  bool put_read() {
+    ceph_assert(state == RWREAD);
+    return dec();
+  }
+  bool put_write() {
+    ceph_assert(state == RWWRITE);
+    return dec();
+  }
+  bool put_excl() {
+    ceph_assert(state == RWEXCL);
+    return dec();
+  }
+  void inc_waiters() {
+    ++waiters;
+  }
+  void release_waiters() {
+    waiters = 0;
+  }
+  void dec_waiters(int count) {
+    ceph_assert(waiters >= count);
+    waiters -= count;
+  }
+  bool empty() const { return state == RWNONE; }
+
+  bool get_snaptrimmer_write(bool mark_if_unsuccessful) {
+    if (get_write_lock()) {
+      return true;
+    } else {
+      if (mark_if_unsuccessful)
+	snaptrimmer_write_marker = true;
+      return false;
+    }
+  }
+  bool get_recovery_read() {
+    recovery_read_marker = true;
+    if (get_read_lock()) {
+      return true;
+    }
+    return false;
+  }
+};
+
+inline std::ostream& operator<<(std::ostream& out, const RWState& rw)
+{
+  return out << "rwstate(" << rw.get_state_name()
+	     << " n=" << rw.count
+	     << " w=" << rw.waiters
+	     << ")";
+}