1 | /* SPDX-License-Identifier: BSD-2-Clause */ |
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2 | |
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3 | /** |
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4 | * @file |
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5 | * |
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6 | * @ingroup RTEMSScoreMessageQueue |
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7 | * |
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8 | * @brief This source file contains the implementation of |
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9 | * _CORE_message_queue_Flush(). |
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10 | */ |
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11 | |
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12 | /* |
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13 | * COPYRIGHT (c) 1989-1999. |
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14 | * On-Line Applications Research Corporation (OAR). |
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15 | * |
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16 | * Redistribution and use in source and binary forms, with or without |
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17 | * modification, are permitted provided that the following conditions |
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18 | * are met: |
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19 | * 1. Redistributions of source code must retain the above copyright |
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20 | * notice, this list of conditions and the following disclaimer. |
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21 | * 2. Redistributions in binary form must reproduce the above copyright |
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22 | * notice, this list of conditions and the following disclaimer in the |
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23 | * documentation and/or other materials provided with the distribution. |
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24 | * |
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25 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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26 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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27 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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28 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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29 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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30 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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31 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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32 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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33 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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34 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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35 | * POSSIBILITY OF SUCH DAMAGE. |
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36 | */ |
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37 | |
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38 | #ifdef HAVE_CONFIG_H |
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39 | #include "config.h" |
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40 | #endif |
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41 | |
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42 | #include <rtems/score/coremsgimpl.h> |
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43 | |
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44 | uint32_t _CORE_message_queue_Flush( |
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45 | CORE_message_queue_Control *the_message_queue, |
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46 | Thread_queue_Context *queue_context |
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47 | ) |
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48 | { |
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49 | Chain_Node *inactive_head; |
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50 | Chain_Node *inactive_first; |
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51 | Chain_Node *message_queue_first; |
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52 | Chain_Node *message_queue_last; |
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53 | uint32_t count; |
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54 | |
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55 | /* |
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56 | * Currently, RTEMS supports no API that has both flush and blocking |
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57 | * sends. Thus, this routine assumes that there are no senders |
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58 | * blocked waiting to send messages. In the event, that an API is |
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59 | * added that can flush a message queue when threads are blocked |
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60 | * waiting to send, there are two basic behaviors envisioned: |
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61 | * |
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62 | * (1) The thread queue of pending senders is a logical extension |
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63 | * of the pending message queue. In this case, it should be |
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64 | * flushed using the _Thread_queue_Flush_critical() service with a status |
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65 | * such as CORE_MESSAGE_QUEUE_SENDER_FLUSHED (which currently does |
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66 | * not exist). This can be implemented without changing the "big-O" |
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67 | * of the message flushing part of the routine. |
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68 | * |
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69 | * (2) Only the actual messages queued should be purged. In this case, |
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70 | * the blocked sender threads must be allowed to send their messages. |
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71 | * In this case, the implementation will be forced to individually |
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72 | * dequeue the senders and queue their messages. This will force |
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73 | * this routine to have "big O(n)" where n is the number of blocked |
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74 | * senders. If there are more messages pending than senders blocked, |
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75 | * then the existing flush code can be used to dispose of the remaining |
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76 | * pending messages. |
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77 | * |
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78 | * For now, though, we are very happy to have a small routine with |
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79 | * fixed execution time that only deals with pending messages. |
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80 | */ |
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81 | |
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82 | _CORE_message_queue_Acquire_critical( the_message_queue, queue_context ); |
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83 | |
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84 | count = the_message_queue->number_of_pending_messages; |
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85 | if ( count != 0 ) { |
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86 | the_message_queue->number_of_pending_messages = 0; |
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87 | |
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88 | inactive_head = _Chain_Head( &the_message_queue->Inactive_messages ); |
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89 | inactive_first = inactive_head->next; |
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90 | message_queue_first = _Chain_First( &the_message_queue->Pending_messages ); |
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91 | message_queue_last = _Chain_Last( &the_message_queue->Pending_messages ); |
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92 | |
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93 | inactive_head->next = message_queue_first; |
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94 | message_queue_last->next = inactive_first; |
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95 | inactive_first->previous = message_queue_last; |
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96 | message_queue_first->previous = inactive_head; |
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97 | |
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98 | _Chain_Initialize_empty( &the_message_queue->Pending_messages ); |
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99 | } |
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100 | |
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101 | _CORE_message_queue_Release( the_message_queue, queue_context ); |
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102 | return count; |
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103 | } |
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