ceph/src/common/RefCountedObj.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #ifndef CEPH_REFCOUNTEDOBJ_H
  16 #define CEPH_REFCOUNTEDOBJ_H
  17
  18 #include "common/Mutex.h"
  19 #include "common/Cond.h"
  20 #include "common/ceph_context.h"
  21 #include "common/valgrind.h"
  22
  23 // re-include our assert to clobber the system one; fix dout:
  24 #include "include/assert.h"
  25
  26 struct RefCountedObject {
  27 private:
  28   mutable std::atomic<uint64_t> nref;
  29   CephContext *cct;
  30 public:
  31   RefCountedObject(CephContext *c = NULL, int n=1) : nref(n), cct(c) {}
  32   virtual ~RefCountedObject() {
  33     assert(nref == 0);
  34   }
  35
  36   const RefCountedObject *get() const {
  37     int v = ++nref;
  38     if (cct)
  39       lsubdout(cct, refs, 1) << "RefCountedObject::get " << this << " "
  40                              << (v - 1) << " -> " << v
  41                              << dendl;
  42     return this;
  43   }
  44   RefCountedObject *get() {
  45     int v = ++nref;
  46     if (cct)
  47       lsubdout(cct, refs, 1) << "RefCountedObject::get " << this << " "
  48                              << (v - 1) << " -> " << v
  49                              << dendl;
  50     return this;
  51   }
  52   void put() const {
  53     CephContext *local_cct = cct;
  54     int v = --nref;
  55     if (v == 0) {
  56       ANNOTATE_HAPPENS_AFTER(&nref);
  57       ANNOTATE_HAPPENS_BEFORE_FORGET_ALL(&nref);
  58       delete this;
  59     } else {
  60       ANNOTATE_HAPPENS_BEFORE(&nref);
  61     }
  62     if (local_cct)
  63       lsubdout(local_cct, refs, 1) << "RefCountedObject::put " << this << " "
  64                                    << (v + 1) << " -> " << v
  65                                    << dendl;
  66   }
  67   void set_cct(CephContext *c) {
  68     cct = c;
  69   }
  70
  71   uint64_t get_nref() const {
  72     return nref;
  73   }
  74 };
  75
  76 /**
  77  * RefCountedCond
  78  *
  79  *  a refcounted condition, will be removed when all references are dropped
  80  */
  81
  82 struct RefCountedCond : public RefCountedObject {
  83   bool complete;
  84   Mutex lock;
  85   Cond cond;
  86   int rval;
  87
  88   RefCountedCond() : complete(false), lock("RefCountedCond"), rval(0) {}
  89
  90   int wait() {
  91     Mutex::Locker l(lock);
  92     while (!complete) {
  93       cond.Wait(lock);
  94     }
  95     return rval;
  96   }
  97
  98   void done(int r) {
  99     Mutex::Locker l(lock);
 100     rval = r;
 101     complete = true;
 102     cond.SignalAll();
 103   }
 104
 105   void done() {
 106     done(0);
 107   }
 108 };
 109
 110 /**
 111  * RefCountedWaitObject
 112  *
 113  * refcounted object that allows waiting for the object's last reference.
 114  * Any referrer can either put or put_wait(). A simple put() will return
 115  * immediately, a put_wait() will return only when the object is destroyed.
 116  * e.g., useful when we want to wait for a specific event completion. We
 117  * use RefCountedCond, as the condition can be referenced after the object
 118  * destruction.
 119  *
 120  */
 121 struct RefCountedWaitObject {
 122   std::atomic<uint64_t> nref = { 1 };
 123   RefCountedCond *c;
 124
 125   RefCountedWaitObject() {
 126     c = new RefCountedCond;
 127   }
 128   virtual ~RefCountedWaitObject() {
 129     c->put();
 130   }
 131
 132   RefCountedWaitObject *get() {
 133     nref++;
 134     return this;
 135   }
 136
 137   bool put() {
 138     bool ret = false;
 139     RefCountedCond *cond = c;
 140     cond->get();
 141     if (--nref == 0) {
 142       cond->done();
 143       delete this;
 144       ret = true;
 145     }
 146     cond->put();
 147     return ret;
 148   }
 149
 150   void put_wait() {
 151     RefCountedCond *cond = c;
 152
 153     cond->get();
 154     if (--nref == 0) {
 155       cond->done();
 156       delete this;
 157     } else {
 158       cond->wait();
 159     }
 160     cond->put();
 161   }
 162 };
 163
 164 void intrusive_ptr_add_ref(const RefCountedObject *p);
 165 void intrusive_ptr_release(const RefCountedObject *p);
 166
 167 #endif