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1 /*
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2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // There are various techniques that require threads to be able to log
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26 // addresses. For example, a generational write barrier might log
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27 // the addresses of modified old-generation objects. This type supports
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28 // this operation.
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29
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30 class PtrQueueSet;
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31
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32 class PtrQueue: public CHeapObj {
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33
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34 protected:
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35 // The ptr queue set to which this queue belongs.
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36 PtrQueueSet* _qset;
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37
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38 // Whether updates should be logged.
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39 bool _active;
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40
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41 // The buffer.
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42 void** _buf;
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43 // The index at which an object was last enqueued. Starts at "_sz"
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44 // (indicating an empty buffer) and goes towards zero.
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45 size_t _index;
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46
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47 // The size of the buffer.
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48 size_t _sz;
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49
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50 // If true, the queue is permanent, and doesn't need to deallocate
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51 // its buffer in the destructor (since that obtains a lock which may not
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52 // be legally locked by then.
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53 bool _perm;
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54
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55 // If there is a lock associated with this buffer, this is that lock.
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56 Mutex* _lock;
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57
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58 PtrQueueSet* qset() { return _qset; }
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59
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60 public:
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61 // Initialize this queue to contain a null buffer, and be part of the
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62 // given PtrQueueSet.
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63 PtrQueue(PtrQueueSet*, bool perm = false);
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64 // Release any contained resources.
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65 ~PtrQueue();
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66
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67 // Associate a lock with a ptr queue.
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68 void set_lock(Mutex* lock) { _lock = lock; }
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69
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70 void reset() { if (_buf != NULL) _index = _sz; }
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71
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72 // Enqueues the given "obj".
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73 void enqueue(void* ptr) {
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74 if (!_active) return;
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75 else enqueue_known_active(ptr);
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76 }
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77
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78 inline void handle_zero_index();
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79 void locking_enqueue_completed_buffer(void** buf);
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80
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81 void enqueue_known_active(void* ptr);
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82
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83 size_t size() {
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84 assert(_sz >= _index, "Invariant.");
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85 return _buf == NULL ? 0 : _sz - _index;
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86 }
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87
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88 // Set the "active" property of the queue to "b". An enqueue to an
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89 // inactive thread is a no-op. Setting a queue to inactive resets its
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90 // log to the empty state.
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91 void set_active(bool b) {
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92 _active = b;
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93 if (!b && _buf != NULL) {
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94 _index = _sz;
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95 } else if (b && _buf != NULL) {
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96 assert(_index == _sz, "invariant: queues are empty when activated.");
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97 }
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98 }
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99
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100 static int byte_index_to_index(int ind) {
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101 assert((ind % oopSize) == 0, "Invariant.");
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102 return ind / oopSize;
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103 }
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104
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105 static int index_to_byte_index(int byte_ind) {
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106 return byte_ind * oopSize;
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107 }
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108
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109 // To support compiler.
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110 static ByteSize byte_offset_of_index() {
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111 return byte_offset_of(PtrQueue, _index);
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112 }
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113 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); }
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114
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115 static ByteSize byte_offset_of_buf() {
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116 return byte_offset_of(PtrQueue, _buf);
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117 }
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118 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); }
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119
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120 static ByteSize byte_offset_of_active() {
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121 return byte_offset_of(PtrQueue, _active);
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122 }
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123 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); }
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124
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125 };
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126
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127 // A PtrQueueSet represents resources common to a set of pointer queues.
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128 // In particular, the individual queues allocate buffers from this shared
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129 // set, and return completed buffers to the set.
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130 // All these variables are are protected by the TLOQ_CBL_mon. XXX ???
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131 class PtrQueueSet: public CHeapObj {
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132
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133 protected:
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134
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135 class CompletedBufferNode: public CHeapObj {
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136 public:
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137 void** buf;
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138 size_t index;
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139 CompletedBufferNode* next;
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140 CompletedBufferNode() : buf(NULL),
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141 index(0), next(NULL){ }
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142 };
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143
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144 Monitor* _cbl_mon; // Protects the fields below.
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145 CompletedBufferNode* _completed_buffers_head;
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146 CompletedBufferNode* _completed_buffers_tail;
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147 size_t _n_completed_buffers;
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148 size_t _process_completed_threshold;
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149 volatile bool _process_completed;
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150
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151 // This (and the interpretation of the first element as a "next"
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152 // pointer) are protected by the TLOQ_FL_lock.
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153 Mutex* _fl_lock;
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154 void** _buf_free_list;
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155 size_t _buf_free_list_sz;
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156
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157 // The size of all buffers in the set.
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158 size_t _sz;
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159
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160 bool _all_active;
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161
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162 // If true, notify_all on _cbl_mon when the threshold is reached.
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163 bool _notify_when_complete;
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164
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165 // Maximum number of elements allowed on completed queue: after that,
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166 // enqueuer does the work itself. Zero indicates no maximum.
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167 int _max_completed_queue;
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168
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169 int completed_buffers_list_length();
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170 void assert_completed_buffer_list_len_correct_locked();
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171 void assert_completed_buffer_list_len_correct();
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172
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173 protected:
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174 // A mutator thread does the the work of processing a buffer.
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175 // Returns "true" iff the work is complete (and the buffer may be
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176 // deallocated).
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177 virtual bool mut_process_buffer(void** buf) {
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178 ShouldNotReachHere();
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179 return false;
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180 }
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181
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182 public:
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183 // Create an empty ptr queue set.
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184 PtrQueueSet(bool notify_when_complete = false);
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185
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186 // Because of init-order concerns, we can't pass these as constructor
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187 // arguments.
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188 void initialize(Monitor* cbl_mon, Mutex* fl_lock,
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189 int max_completed_queue = 0) {
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190 _max_completed_queue = max_completed_queue;
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191 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?");
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192 _cbl_mon = cbl_mon; _fl_lock = fl_lock;
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193 }
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194
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195 // Return an empty oop array of size _sz (required to be non-zero).
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196 void** allocate_buffer();
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197
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198 // Return an empty buffer to the free list. The "buf" argument is
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199 // required to be a pointer to the head of an array of length "_sz".
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200 void deallocate_buffer(void** buf);
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201
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202 // Declares that "buf" is a complete buffer.
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203 void enqueue_complete_buffer(void** buf, size_t index = 0,
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204 bool ignore_max_completed = false);
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205
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206 bool completed_buffers_exist_dirty() {
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207 return _n_completed_buffers > 0;
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208 }
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209
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210 bool process_completed_buffers() { return _process_completed; }
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211
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212 bool active() { return _all_active; }
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213
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214 // Set the buffer size. Should be called before any "enqueue" operation
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215 // can be called. And should only be called once.
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216 void set_buffer_size(size_t sz);
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217
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218 // Get the buffer size.
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219 size_t buffer_size() { return _sz; }
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220
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221 // Set the number of completed buffers that triggers log processing.
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222 void set_process_completed_threshold(size_t sz);
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223
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224 // Must only be called at a safe point. Indicates that the buffer free
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225 // list size may be reduced, if that is deemed desirable.
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226 void reduce_free_list();
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227
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228 size_t completed_buffers_num() { return _n_completed_buffers; }
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229 };
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