Ewout van Bekkum | f4da489 | 2021-03-05 15:05:37 -0800 | [diff] [blame] | 1 | // Copyright 2021 The Pigweed Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| 4 | // use this file except in compliance with the License. You may obtain a copy of |
| 5 | // the License at |
| 6 | // |
| 7 | // https://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| 11 | // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| 12 | // License for the specific language governing permissions and limitations under |
| 13 | // the License. |
| 14 | #include "pw_thread/thread.h" |
| 15 | |
Wyatt Hepler | f298de4 | 2021-03-19 15:06:36 -0700 | [diff] [blame] | 16 | #include "pw_assert/check.h" |
Ewout van Bekkum | f4da489 | 2021-03-05 15:05:37 -0800 | [diff] [blame] | 17 | #include "pw_preprocessor/compiler.h" |
| 18 | #include "pw_thread/id.h" |
| 19 | #include "pw_thread_threadx/config.h" |
| 20 | #include "pw_thread_threadx/context.h" |
| 21 | #include "pw_thread_threadx/options.h" |
| 22 | #include "tx_event_flags.h" |
| 23 | |
| 24 | using pw::thread::threadx::Context; |
| 25 | |
| 26 | namespace pw::thread { |
| 27 | namespace { |
| 28 | #if PW_THREAD_JOINING_ENABLED |
| 29 | constexpr ULONG kThreadDoneBit = 1; |
| 30 | #endif // PW_THREAD_JOINING_ENABLED |
| 31 | } // namespace |
| 32 | |
Ewout van Bekkum | cd765c0 | 2021-05-14 10:28:26 -0700 | [diff] [blame] | 33 | void Context::ThreadEntryPoint(ULONG void_context_ptr) { |
Ewout van Bekkum | f4da489 | 2021-03-05 15:05:37 -0800 | [diff] [blame] | 34 | Context& context = *reinterpret_cast<Context*>(void_context_ptr); |
Ewout van Bekkum | cd765c0 | 2021-05-14 10:28:26 -0700 | [diff] [blame] | 35 | |
| 36 | // Invoke the user's thread function. This may never return. |
| 37 | context.user_thread_entry_function_(context.user_thread_entry_arg_); |
Ewout van Bekkum | f4da489 | 2021-03-05 15:05:37 -0800 | [diff] [blame] | 38 | |
| 39 | // Raise our preemption threshold as a thread only critical section to guard |
| 40 | // against join() and detach(). |
| 41 | UINT original_preemption_threshold = TX_MAX_PRIORITIES; // Invalid. |
| 42 | UINT preemption_success = tx_thread_preemption_change( |
| 43 | &context.tcb(), 0, &original_preemption_threshold); |
| 44 | PW_DCHECK_UINT_EQ(TX_SUCCESS, |
| 45 | preemption_success, |
| 46 | "Failed to enter thread critical section"); |
| 47 | if (context.detached()) { |
| 48 | // There is no threadsafe way to re-use detached threads, as there's no way |
| 49 | // to invoke tx_thread_delete() from the running thread! Joining MUST be |
| 50 | // used for this. However to enable unit test coverage we go ahead and clear |
| 51 | // this. |
| 52 | context.set_in_use(false); |
| 53 | |
| 54 | #if PW_THREAD_JOINING_ENABLED |
Ewout van Bekkum | cd765c0 | 2021-05-14 10:28:26 -0700 | [diff] [blame] | 55 | // If the thread handle was detached before the thread finished execution, |
| 56 | // i.e. got here, then we are responsible for cleaning up the join event |
| 57 | // group. |
Ewout van Bekkum | f4da489 | 2021-03-05 15:05:37 -0800 | [diff] [blame] | 58 | const UINT event_group_result = |
| 59 | tx_event_flags_delete(&context.join_event_group()); |
| 60 | PW_DCHECK_UINT_EQ(TX_SUCCESS, |
| 61 | event_group_result, |
| 62 | "Failed to delete the join event group"); |
| 63 | #endif // PW_THREAD_JOINING_ENABLED |
| 64 | |
| 65 | // Note that we do not have to restore our preemption threshold as this |
| 66 | // thread is completing execution. |
| 67 | |
| 68 | // WARNING: The thread at this point continues to be registered with the |
| 69 | // kernel in TX_COMPLETED state, as tx_thread_delete cannot be invoked! |
| 70 | return; |
| 71 | } |
| 72 | |
| 73 | // Otherwise the task finished before the thread was detached or joined, defer |
| 74 | // cleanup to Thread's join() or detach(). |
| 75 | context.set_thread_done(); |
| 76 | UINT unused = 0; |
| 77 | preemption_success = tx_thread_preemption_change( |
| 78 | &context.tcb(), original_preemption_threshold, &unused); |
| 79 | PW_DCHECK_UINT_EQ(TX_SUCCESS, |
| 80 | preemption_success, |
| 81 | "Failed to leave thread critical section"); |
| 82 | |
| 83 | #if PW_THREAD_JOINING_ENABLED |
| 84 | const UINT result = |
| 85 | tx_event_flags_set(&context.join_event_group(), kThreadDoneBit, TX_OR); |
| 86 | PW_DCHECK_UINT_EQ(TX_SUCCESS, result, "Failed to set the join event"); |
| 87 | #endif // PW_THREAD_JOINING_ENABLED |
| 88 | return; |
| 89 | } |
| 90 | |
| 91 | void Context::DeleteThread(Context& context) { |
| 92 | // Stop the other task first. |
| 93 | UINT thread_result = tx_thread_terminate(&context.tcb()); |
| 94 | PW_CHECK_UINT_EQ(TX_SUCCESS, thread_result, "Failed to terminate the thread"); |
| 95 | |
| 96 | // Delete the thread, removing it out of the kernel. |
| 97 | thread_result = tx_thread_delete(&context.tcb()); |
| 98 | PW_CHECK_UINT_EQ(TX_SUCCESS, thread_result, "Failed to delete the thread"); |
| 99 | |
| 100 | // Mark the context as unused for potential later re-use. |
| 101 | context.set_in_use(false); |
| 102 | |
| 103 | #if PW_THREAD_JOINING_ENABLED |
| 104 | // Just in case someone abused our API, ensure their use of the event group is |
| 105 | // properly handled by the kernel regardless. |
| 106 | const UINT event_group_result = |
| 107 | tx_event_flags_delete(&context.join_event_group()); |
| 108 | PW_DCHECK_UINT_EQ( |
| 109 | TX_SUCCESS, event_group_result, "Failed to delete the join event group"); |
| 110 | #endif // PW_THREAD_JOINING_ENABLED |
| 111 | } |
| 112 | |
| 113 | Thread::Thread(const thread::Options& facade_options, |
| 114 | ThreadRoutine entry, |
| 115 | void* arg) |
| 116 | : native_type_(nullptr) { |
| 117 | // Cast the generic facade options to the backend specific option of which |
| 118 | // only one type can exist at compile time. |
| 119 | auto options = static_cast<const threadx::Options&>(facade_options); |
| 120 | PW_DCHECK_NOTNULL(options.context(), "The Context is not optional"); |
| 121 | native_type_ = options.context(); |
| 122 | |
| 123 | // Can't use a context more than once. |
| 124 | PW_DCHECK(!native_type_->in_use()); |
| 125 | |
| 126 | // Reset the state of the static context in case it was re-used. |
Ewout van Bekkum | 5dac14a | 2021-05-07 14:11:22 -0700 | [diff] [blame] | 127 | native_type_->set_in_use(true); |
Ewout van Bekkum | f4da489 | 2021-03-05 15:05:37 -0800 | [diff] [blame] | 128 | native_type_->set_detached(false); |
| 129 | native_type_->set_thread_done(false); |
| 130 | #if PW_THREAD_JOINING_ENABLED |
| 131 | static const char* join_event_group_name = "pw::Thread"; |
| 132 | const UINT event_group_result = |
| 133 | tx_event_flags_create(&options.context()->join_event_group(), |
| 134 | const_cast<char*>(join_event_group_name)); |
| 135 | PW_DCHECK_UINT_EQ( |
| 136 | TX_SUCCESS, event_group_result, "Failed to create the join event group"); |
| 137 | #endif // PW_THREAD_JOINING_ENABLED |
| 138 | |
| 139 | // Copy over the thread name. |
| 140 | native_type_->set_name(options.name()); |
| 141 | |
| 142 | // In order to support functions which return and joining, a delegate is |
| 143 | // deep copied into the context with a small wrapping function to actually |
| 144 | // invoke the task with its arg. |
| 145 | native_type_->set_thread_routine(entry, arg); |
| 146 | |
| 147 | const UINT thread_result = |
| 148 | tx_thread_create(&options.context()->tcb(), |
| 149 | const_cast<char*>(native_type_->name()), |
Ewout van Bekkum | cd765c0 | 2021-05-14 10:28:26 -0700 | [diff] [blame] | 150 | Context::ThreadEntryPoint, |
Ewout van Bekkum | f4da489 | 2021-03-05 15:05:37 -0800 | [diff] [blame] | 151 | reinterpret_cast<ULONG>(native_type_), |
| 152 | options.context()->stack().data(), |
| 153 | options.context()->stack().size_bytes(), |
| 154 | options.priority(), |
| 155 | options.preemption_threshold(), |
| 156 | options.time_slice_interval(), |
| 157 | TX_AUTO_START); |
| 158 | PW_CHECK_UINT_EQ(TX_SUCCESS, thread_result, "Failed to create the thread"); |
| 159 | } |
| 160 | |
| 161 | void Thread::detach() { |
| 162 | PW_CHECK(joinable()); |
| 163 | |
| 164 | tx_thread_suspend(&native_type_->tcb()); |
| 165 | native_type_->set_detached(); |
| 166 | const bool thread_done = native_type_->thread_done(); |
| 167 | tx_thread_resume(&native_type_->tcb()); |
| 168 | |
| 169 | if (thread_done) { |
Ewout van Bekkum | cd765c0 | 2021-05-14 10:28:26 -0700 | [diff] [blame] | 170 | // The task finished (hit end of Context::ThreadEntryPoint) before we |
| 171 | // invoked detach, clean up the thread. |
Ewout van Bekkum | f4da489 | 2021-03-05 15:05:37 -0800 | [diff] [blame] | 172 | Context::DeleteThread(*native_type_); |
| 173 | } else { |
| 174 | // We're detaching before the task finished, defer cleanup to the task at |
Ewout van Bekkum | cd765c0 | 2021-05-14 10:28:26 -0700 | [diff] [blame] | 175 | // the end of Context::ThreadEntryPoint. |
Ewout van Bekkum | f4da489 | 2021-03-05 15:05:37 -0800 | [diff] [blame] | 176 | } |
| 177 | |
| 178 | // Update to no longer represent a thread of execution. |
| 179 | native_type_ = nullptr; |
| 180 | } |
| 181 | |
| 182 | #if PW_THREAD_JOINING_ENABLED |
| 183 | void Thread::join() { |
| 184 | PW_CHECK(joinable()); |
| 185 | PW_CHECK(this_thread::get_id() != get_id()); |
| 186 | |
| 187 | ULONG actual_flags = 0; |
| 188 | const UINT result = tx_event_flags_get(&native_type_->join_event_group(), |
| 189 | kThreadDoneBit, |
| 190 | TX_OR_CLEAR, |
| 191 | &actual_flags, |
| 192 | TX_WAIT_FOREVER); |
| 193 | PW_DCHECK_UINT_EQ(TX_SUCCESS, result, "Failed to get the join event"); |
| 194 | |
| 195 | // No need for a critical section here as the thread at this point is |
| 196 | // waiting to be deleted. |
| 197 | Context::DeleteThread(*native_type_); |
| 198 | |
| 199 | // Update to no longer represent a thread of execution. |
| 200 | native_type_ = nullptr; |
| 201 | } |
| 202 | #endif // PW_THREAD_JOINING_ENABLED |
| 203 | |
| 204 | } // namespace pw::thread |