1 /* Copyright (c) 2021-2023. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #ifndef SIMGRID_PLUGIN_PRODUCERCONSUMER_HPP
7 #define SIMGRID_PLUGIN_PRODUCERCONSUMER_HPP
9 #include <simgrid/s4u/Comm.hpp>
10 #include <simgrid/s4u/ConditionVariable.hpp>
11 #include <simgrid/s4u/Mailbox.hpp>
12 #include <simgrid/s4u/Mutex.hpp>
13 #include <xbt/asserts.h>
21 XBT_LOG_EXTERNAL_CATEGORY(producer_consumer);
23 /** Stock implementation of a generic monitored queue to solve the producer-consumer problem */
25 namespace simgrid::plugin {
27 template <typename T> class ProducerConsumer;
28 template <typename T> using ProducerConsumerPtr = boost::intrusive_ptr<ProducerConsumer<T>>;
30 class ProducerConsumerId {
32 static unsigned long pc_id;
35 const std::string id = "ProducerConsumer" + std::to_string(pc_id);
36 ProducerConsumerId() { ++pc_id; }
39 template <typename T> class ProducerConsumer : public ProducerConsumerId {
41 /** This ProducerConsumer plugin can use two different transfer modes:
42 * - TransferMode::MAILBOX: this mode induces a s4u::Comm between the actors doing the calls to put() and get().
43 * If these actors are on the same host, this communication goes through the host's loopback and can thus be
44 * seen as a memory copy. Otherwise, data goes over the network.
45 * - TransferMode::QUEUE: data is internally stored in a std::queue. Putting and getting data to and from this
46 * data structure has a zero-cost in terms of simulated time.
47 * Both modes guarantee that the data is consumed in the order it has been produced. However, when data goes
48 * through the network, s4u::Comm are started in the right order, but may complete in a different order depending
49 * the characteristics of the different interconnections between host pairs.
51 enum class TransferMode { MAILBOX = 0, QUEUE };
54 /* Implementation of a Monitor to handle the data exchanges */
56 s4u::ConditionVariablePtr can_put_;
57 s4u::ConditionVariablePtr can_get_;
59 /* data containers for each of the transfer modes */
60 s4u::Mailbox* mbox_ = nullptr;
61 std::queue<T*> queue_;
63 unsigned int max_queue_size_ = 1;
64 TransferMode tmode_ = TransferMode::MAILBOX;
66 /* Refcounting management */
67 std::atomic_int_fast32_t refcount_{0};
68 friend void intrusive_ptr_add_ref(ProducerConsumer* pc) { pc->refcount_.fetch_add(1, std::memory_order_acq_rel); }
70 friend void intrusive_ptr_release(ProducerConsumer* pc)
72 if (pc->refcount_.fetch_sub(1, std::memory_order_release) == 1) {
73 std::atomic_thread_fence(std::memory_order_acquire);
78 explicit ProducerConsumer(unsigned int max_queue_size) : max_queue_size_(max_queue_size)
80 xbt_assert(max_queue_size > 0, "Max queue size of 0 is not allowed");
82 mutex_ = s4u::Mutex::create();
83 can_put_ = s4u::ConditionVariable::create();
84 can_get_ = s4u::ConditionVariable::create();
86 if (tmode_ == TransferMode::MAILBOX)
87 mbox_ = s4u::Mailbox::by_name(id);
89 ~ProducerConsumer() = default;
92 /** Creation of the monitored queue. Its size can be bounded by passing a strictly positive value to 'max_queue_size'
93 * as parameter. Calling 'create()' means that the queue size is (virtually) infinite.
95 static ProducerConsumerPtr<T> create(unsigned int max_queue_size = UINT_MAX)
97 return ProducerConsumerPtr<T>(new ProducerConsumer<T>(max_queue_size));
100 /** This method is intended more to set the maximum queue size in a fluent way than changing the size during the
101 * utilization of the ProducerConsumer. Hence, the modification occurs in a critical section to prevent
104 ProducerConsumer* set_max_queue_size(unsigned int max_queue_size)
106 const std::scoped_lock lock(*mutex_);
107 max_queue_size_ = max_queue_size;
111 unsigned int get_max_queue_size() const { return max_queue_size_; }
113 /** The underlying data container (and transfer mode) can only be modified when the queue is empty.*/
114 ProducerConsumer* set_transfer_mode(TransferMode new_mode)
116 if (tmode_ == new_mode) /* No change, do nothing */
119 xbt_assert(empty(), "cannot change transfer mode when some data is in queue");
120 if (new_mode == TransferMode::MAILBOX) {
121 mbox_ = s4u::Mailbox::by_name(id);
128 std::string get_transfer_mode() const { return tmode_ == TransferMode::MAILBOX ? "mailbox" : "queue"; }
130 /** Container-agnostic size() method */
131 unsigned int size() { return tmode_ == TransferMode::MAILBOX ? mbox_->size() : queue_.size(); }
133 /** Container-agnostic empty() method */
134 bool empty() { return tmode_ == TransferMode::MAILBOX ? mbox_->empty() : queue_.empty(); }
136 /** Asynchronous put() of a data item of a given size
137 * - TransferMode::MAILBOX: if put_async is called directly from user code, it can be considered to be done in a
138 * fire-and-forget mode. No need to save the s4u::CommPtr.
139 * - TransferMode::QUEUE: the data is simply pushed into the queue.
141 s4u::CommPtr put_async(T* data, size_t simulated_size_in_bytes)
143 std::unique_lock lock(*mutex_);
144 s4u::CommPtr comm = nullptr;
145 XBT_CVERB(producer_consumer, (size() < max_queue_size_) ? "can put" : "must wait");
147 while (size() >= max_queue_size_)
148 can_put_->wait(lock);
149 if (tmode_ == TransferMode::MAILBOX) {
150 comm = mbox_->put_init(data, simulated_size_in_bytes)
154 can_get_->notify_all();
158 /** Synchronous put() of a data item of a given size
159 * - TransferMode::MAILBOX: the caller must wait for the induced communication with the getter of the data to be
160 * complete to continue with its execution. This wait is done outside of the monitor to prevent serialization.
161 * - TransferMode::QUEUE: the behavior is exactly the same as put_async: data is simply pushed into the queue.
163 void put(T* data, size_t simulated_size_in_bytes)
165 s4u::CommPtr comm = put_async(data, simulated_size_in_bytes);
167 XBT_CDEBUG(producer_consumer, "Waiting for the data to be consumed");
172 /** Asynchronous get() of a 'data'
173 * - TransferMode::MAILBOX: the caller is returned a s4u::CommPtr onto which it can wait when the data is really
175 * - TransferMode::QUEUE: the data is simply popped from the queue and directly available. Better to call get() in
176 * this transfer mode.
178 s4u::CommPtr get_async(T** data)
180 std::unique_lock lock(*mutex_);
181 s4u::CommPtr comm = nullptr;
182 XBT_CVERB(producer_consumer, empty() ? "must wait" : "can get");
184 can_get_->wait(lock);
185 if (tmode_ == TransferMode::MAILBOX)
186 comm = mbox_->get_init()
187 ->set_dst_data(reinterpret_cast<void**>(data), sizeof(void*))
190 *data = queue_.front();
193 can_put_->notify_all();
198 /** Synchronous get() of a 'data'
199 * - TransferMode::MAILBOX: the caller waits (outside the monitor to prevent serialization) for the induced
200 * communication to be complete to continue with its execution.
201 * - TransferMode::QUEUE: the behavior is exactly the same as get_async: data is simply popped from the queue and
202 * directly available to the caller.
207 if (s4u::CommPtr comm = get_async(&data)) {
208 XBT_CDEBUG(producer_consumer, "Waiting for the data to arrive");
211 XBT_CDEBUG(producer_consumer, "data is available");
216 } // namespace simgrid::plugin
218 #endif // SIMGRID_PLUGIN_PRODUCERCONSUMER_HPP