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diff --git a/src/common/Cond.h b/src/common/Cond.h
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+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+
+#ifndef CEPH_COND_H
+#define CEPH_COND_H
+
+#include "common/Clock.h"
+#include "common/ceph_mutex.h"
+#include "include/Context.h"
+
+/**
+ * context to signal a cond
+ *
+ * Generic context to signal a cond and store the return value.  We
+ * assume the caller is holding the appropriate lock.
+ */
+class C_Cond : public Context {
+  ceph::condition_variable& cond;   ///< Cond to signal
+  bool *done;   ///< true if finish() has been called
+  int *rval;    ///< return value
+public:
+  C_Cond(ceph::condition_variable &c, bool *d, int *r) : cond(c), done(d), rval(r) {
+    *done = false;
+  }
+  void finish(int r) override {
+    *done = true;
+    *rval = r;
+    cond.notify_all();
+  }
+};
+
+/**
+ * context to signal a cond, protected by a lock
+ *
+ * Generic context to signal a cond under a specific lock. We take the
+ * lock in the finish() callback, so the finish() caller must not
+ * already hold it.
+ */
+class C_SafeCond : public Context {
+  ceph::mutex& lock;    ///< Mutex to take
+  ceph::condition_variable& cond;     ///< Cond to signal
+  bool *done;     ///< true after finish() has been called
+  int *rval;      ///< return value (optional)
+public:
+  C_SafeCond(ceph::mutex& l, ceph::condition_variable& c, bool *d, int *r=0)
+    : lock(l), cond(c), done(d), rval(r) {
+    *done = false;
+  }
+  void finish(int r) override {
+    std::lock_guard l{lock};
+    if (rval)
+      *rval = r;
+    *done = true;
+    cond.notify_all();
+  }
+};
+
+/**
+ * Context providing a simple wait() mechanism to wait for completion
+ *
+ * The context will not be deleted as part of complete and must live
+ * until wait() returns.
+ */
+class C_SaferCond : public Context {
+  ceph::mutex lock;  ///< Mutex to take
+  ceph::condition_variable cond;     ///< Cond to signal
+  bool done = false; ///< true after finish() has been called
+  int rval = 0;      ///< return value
+public:
+  C_SaferCond() :
+    C_SaferCond("C_SaferCond")
+  {}
+  explicit C_SaferCond(const std::string &name)
+    : lock(ceph::make_mutex(name)) {}
+  void finish(int r) override { complete(r); }
+
+  /// We overload complete in order to not delete the context
+  void complete(int r) override {
+    std::lock_guard l(lock);
+    done = true;
+    rval = r;
+    cond.notify_all();
+  }
+
+  /// Returns rval once the Context is called
+  int wait() {
+    std::unique_lock l{lock};
+    cond.wait(l, [this] { return done;});
+    return rval;
+  }
+
+  /// Wait until the \c secs expires or \c complete() is called
+  int wait_for(double secs) {
+    return wait_for(ceph::make_timespan(secs));
+  }
+
+  int wait_for(ceph::timespan secs) {
+    std::unique_lock l{lock};
+    if (done) {
+      return rval;
+    }
+    if (cond.wait_for(l, secs, [this] { return done; })) {
+      return rval;
+    } else {
+      return ETIMEDOUT;
+    }
+  }
+};
+
+#endif