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| 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #ifndef COMPONENTS_SCHEDULER_PROMISES_PROMISE_INTERNAL_H_ |
| 6 #define COMPONENTS_SCHEDULER_PROMISES_PROMISE_INTERNAL_H_ |
| 7 |
| 8 #include <set> |
| 9 #include <vector> |
| 10 |
| 11 #include "base/macros.h" |
| 12 #include "base/memory/ref_counted.h" |
| 13 #include "base/message_loop/message_loop.h" |
| 14 #include "base/single_thread_task_runner.h" |
| 15 #include "components/scheduler/promises/rejectable.h" |
| 16 |
| 17 namespace promise { |
| 18 template <typename R> |
| 19 class Promise; |
| 20 |
| 21 namespace internal { |
| 22 |
| 23 class PromiseExecutor; |
| 24 class ThreadPoolPromiseExecutor; |
| 25 |
| 26 template <typename R> |
| 27 class Promise; |
| 28 |
| 29 class SCHEDULER_EXPORT PromiseBase : public base::RefCounted<PromiseBase> { |
| 30 public: |
| 31 enum class PrerequisitePolicy { ALL, ANY, ALWAYS, NEVER }; |
| 32 |
| 33 explicit PromiseBase(PrerequisitePolicy prerequisite_policy); |
| 34 |
| 35 PromiseBase(std::vector<scoped_refptr<PromiseBase>> prerequisites, |
| 36 PrerequisitePolicy prerequisite_policy); |
| 37 |
| 38 enum class State { |
| 39 NEW, |
| 40 PENDING, |
| 41 PARTIALLY_RESOLVED, |
| 42 RESOLVED, |
| 43 REJECTED, |
| 44 DEPENDENCY_REJECTED, |
| 45 CANCELLED |
| 46 }; |
| 47 |
| 48 State state() const { return state_; } |
| 49 |
| 50 void SetThisAndPrerequisitesAsEager(bool eager); |
| 51 |
| 52 void Cancel(); |
| 53 |
| 54 std::vector<scoped_refptr<PromiseBase>>& prerequisites() { |
| 55 return prerequisites_; |
| 56 } |
| 57 |
| 58 std::set<PromiseBase*>& dependants() { return dependants_; } |
| 59 |
| 60 bool can_run_now() const { return can_run_now_; } |
| 61 |
| 62 bool is_resolved() const { return state() == PromiseBase::State::RESOLVED; } |
| 63 |
| 64 protected: |
| 65 friend class base::RefCounted<PromiseBase>; |
| 66 friend class PromiseExecutor; |
| 67 friend class ThreadPoolPromiseExecutor; |
| 68 |
| 69 virtual ~PromiseBase(); |
| 70 |
| 71 virtual void ExecutorDrivenResolve() = 0; |
| 72 |
| 73 void set_state(State state) { state_ = state; } |
| 74 |
| 75 void SetThisAndPrerequisitesAsShouldRun(PromiseExecutor* executor, |
| 76 bool should_run); |
| 77 |
| 78 void RegisterDynamicDependancy(scoped_refptr<PromiseBase> dependency); |
| 79 |
| 80 bool AllPrerequisitesSatisfied() const; |
| 81 |
| 82 void SchedulePromiseForResolve(); |
| 83 |
| 84 void MarkAsResolved(); |
| 85 void MarkAsRejected(); |
| 86 |
| 87 std::vector<scoped_refptr<PromiseBase>> prerequisites_; |
| 88 std::set<PromiseBase*> dependants_; |
| 89 PromiseExecutor* executor_; |
| 90 State state_; |
| 91 PrerequisitePolicy prerequisite_policy_; |
| 92 bool can_run_now_; |
| 93 int should_run_refcount_; |
| 94 int eager_refcount_; |
| 95 |
| 96 DISALLOW_COPY_AND_ASSIGN(PromiseBase); |
| 97 }; |
| 98 |
| 99 template <typename R> |
| 100 class SCHEDULER_EXPORT Promise : public PromiseBase { |
| 101 public: |
| 102 using ReturnType = R; |
| 103 |
| 104 // RStorageType = (R == void) ? bool : R; |
| 105 // This is useful to avoid the need for partial template specalization. |
| 106 using RStorageType = |
| 107 typename std::conditional<std::is_void<R>::value, bool, R>::type; |
| 108 |
| 109 explicit Promise(PrerequisitePolicy prerequisite_policy) |
| 110 : PromiseBase(prerequisite_policy) {} |
| 111 |
| 112 Promise(std::vector<scoped_refptr<PromiseBase>> prerequisites, |
| 113 PrerequisitePolicy prerequisite_policy) |
| 114 : PromiseBase(std::move(prerequisites), prerequisite_policy) {} |
| 115 |
| 116 template <typename RR = R> |
| 117 enable_if_not_void_t<RR, RR&> GetResolved() { |
| 118 if (r_promise_) |
| 119 return r_promise_->GetResolved(); |
| 120 DCHECK(state() == PromiseBase::State::RESOLVED); |
| 121 return r_; |
| 122 } |
| 123 |
| 124 template <typename RR = R> |
| 125 enable_if_not_void_t<RR, void> Resolve(const RR&& r) { |
| 126 r_ = std::move(r); |
| 127 PromiseBase::MarkAsResolved(); |
| 128 } |
| 129 |
| 130 template <typename RR = R> |
| 131 enable_if_not_void_t<RR, void> Resolve(RR&& r) { |
| 132 r_ = std::move(r); |
| 133 PromiseBase::MarkAsResolved(); |
| 134 } |
| 135 |
| 136 template <typename RR = R> |
| 137 enable_if_void_t<RR, void> Resolve() { |
| 138 PromiseBase::MarkAsResolved(); |
| 139 } |
| 140 |
| 141 void Resolve(::promise::Promise<R> promise) { |
| 142 r_promise_ = std::move(promise.promise_); |
| 143 prerequisite_policy_ = PrerequisitePolicy::ALL; |
| 144 state_ = State::PARTIALLY_RESOLVED; |
| 145 RegisterDynamicDependancy(r_promise_); |
| 146 } |
| 147 |
| 148 bool is_rejected() const { return false; } |
| 149 |
| 150 protected: |
| 151 void ExecutorDrivenResolve() override { NOTREACHED(); } |
| 152 |
| 153 RStorageType r_; |
| 154 scoped_refptr<Promise<R>> r_promise_; |
| 155 |
| 156 virtual ~Promise() {} |
| 157 }; |
| 158 |
| 159 // Partial template specilazation to provide syntatic sugar for Rejectable |
| 160 // promises. |
| 161 template <typename ResolveT, typename RejectT> |
| 162 class SCHEDULER_EXPORT Promise<Rejectable<ResolveT, RejectT>> |
| 163 : public PromiseBase { |
| 164 public: |
| 165 using ReturnType = Rejectable<ResolveT, RejectT>; |
| 166 |
| 167 explicit Promise(PrerequisitePolicy prerequisite_policy) |
| 168 : PromiseBase(prerequisite_policy) {} |
| 169 |
| 170 Promise(std::vector<scoped_refptr<PromiseBase>> prerequisites, |
| 171 PrerequisitePolicy prerequisite_policy) |
| 172 : PromiseBase(std::move(prerequisites), prerequisite_policy) {} |
| 173 |
| 174 ReturnType& GetResolved() { |
| 175 if (r_promise_) |
| 176 return r_promise_->GetResolved(); |
| 177 return r_; |
| 178 } |
| 179 |
| 180 bool is_rejected() const { |
| 181 if (r_promise_) |
| 182 return r_promise_->is_rejected(); |
| 183 return state() == PromiseBase::State::REJECTED; |
| 184 } |
| 185 |
| 186 template <typename RR = ResolveT> |
| 187 enable_if_not_void_t<RR, void> Resolve(const RR& r) { |
| 188 r_.Resolve(r); |
| 189 PromiseBase::MarkAsResolved(); |
| 190 } |
| 191 |
| 192 template <typename RR = ResolveT> |
| 193 enable_if_not_void_t<RR, void> Resolve(RR&& r) { |
| 194 r_.Resolve(std::move(r)); |
| 195 PromiseBase::MarkAsResolved(); |
| 196 } |
| 197 |
| 198 template <typename RR = ResolveT> |
| 199 enable_if_void_t<RR, void> Resolve() { |
| 200 r_.Resolve(); |
| 201 PromiseBase::MarkAsResolved(); |
| 202 } |
| 203 |
| 204 void Resolve(const ReturnType& r) { |
| 205 r_ = r; |
| 206 if (r_.is_resolved()) { |
| 207 PromiseBase::MarkAsResolved(); |
| 208 } else { |
| 209 PromiseBase::MarkAsRejected(); |
| 210 } |
| 211 } |
| 212 |
| 213 void Resolve(ReturnType&& r) { |
| 214 r_ = std::move(r); |
| 215 if (r_.is_resolved()) { |
| 216 PromiseBase::MarkAsResolved(); |
| 217 } else { |
| 218 PromiseBase::MarkAsRejected(); |
| 219 } |
| 220 } |
| 221 |
| 222 template <typename RR = RejectT> |
| 223 enable_if_not_void_t<RR, void> Reject(const RR& r) { |
| 224 r_.Reject(r); |
| 225 PromiseBase::MarkAsRejected(); |
| 226 } |
| 227 |
| 228 template <typename RR = RejectT> |
| 229 enable_if_not_void_t<RR, void> Reject(RR&& r) { |
| 230 r_.Reject(std::move(r)); |
| 231 PromiseBase::MarkAsRejected(); |
| 232 } |
| 233 |
| 234 template <typename RR = RejectT> |
| 235 enable_if_void_t<RR, void> Reject() { |
| 236 r_.Reject(); |
| 237 PromiseBase::MarkAsRejected(); |
| 238 } |
| 239 |
| 240 void Resolve(::promise::Promise<ReturnType> promise) { |
| 241 r_promise_ = std::move(promise.promise_); |
| 242 prerequisite_policy_ = PrerequisitePolicy::ALL; |
| 243 state_ = State::PARTIALLY_RESOLVED; |
| 244 RegisterDynamicDependancy(r_promise_); |
| 245 } |
| 246 |
| 247 protected: |
| 248 void ExecutorDrivenResolve() override { |
| 249 // This can get called if r_promise_ rejects. |
| 250 DCHECK(state_ == PromiseBase::State::DEPENDENCY_REJECTED); |
| 251 } |
| 252 |
| 253 ReturnType r_; |
| 254 scoped_refptr<Promise<ReturnType>> r_promise_; |
| 255 |
| 256 virtual ~Promise() {} |
| 257 }; |
| 258 |
| 259 template <typename R, typename... Args> |
| 260 class FunctionPromise final : public Promise<R> { |
| 261 public: |
| 262 FunctionPromise(base::Callback<R(Args...)> cb) |
| 263 : Promise<R>(PromiseBase::PrerequisitePolicy::ALWAYS), cb_(cb) {} |
| 264 |
| 265 private: |
| 266 ~FunctionPromise() override {} |
| 267 |
| 268 void ExecutorDrivenResolve() override { |
| 269 Promise<R>::Resolve(std::move(cb_.Run())); |
| 270 } |
| 271 |
| 272 base::Callback<R(Args...)> cb_; |
| 273 }; |
| 274 |
| 275 template <typename... Args> |
| 276 class FunctionPromise<void, Args...> final : public Promise<void> { |
| 277 public: |
| 278 FunctionPromise(base::Callback<void(Args...)> cb) |
| 279 : Promise<void>(PromiseBase::PrerequisitePolicy::ALWAYS), cb_(cb) {} |
| 280 |
| 281 private: |
| 282 ~FunctionPromise() override {} |
| 283 |
| 284 void ExecutorDrivenResolve() override { |
| 285 cb_.Run(); |
| 286 Promise<void>::Resolve(); |
| 287 } |
| 288 |
| 289 base::Callback<void(Args...)> cb_; |
| 290 }; |
| 291 |
| 292 // === promise::Race().Then() implementation |
| 293 |
| 294 template <typename ThenR, typename CallbackR, typename AnyPromise> |
| 295 class SCHEDULER_EXPORT RacePromises final : public Promise<ThenR> { |
| 296 public: |
| 297 RacePromises(base::Callback<CallbackR(typename AnyPromise::ReturnType)>&& cb, |
| 298 std::vector<scoped_refptr<PromiseBase>>&& promises) |
| 299 : Promise<ThenR>(std::move(promises), |
| 300 PromiseBase::PrerequisitePolicy::ANY), |
| 301 cb_(std::move(cb)) {} |
| 302 |
| 303 private: |
| 304 template <typename CB = CallbackR> |
| 305 enable_if_not_void_t<CB, void> ResolveInternal(PromiseBase* prerequisite) { |
| 306 Promise<ThenR>::Resolve(std::move(cb_.Run( |
| 307 std::move(static_cast<AnyPromise*>(prerequisite)->GetResolved())))); |
| 308 } |
| 309 |
| 310 template <typename CB = CallbackR> |
| 311 enable_if_void_t<CB, void> ResolveInternal(PromiseBase* prerequisite) { |
| 312 cb_.Run(std::move(static_cast<AnyPromise*>(prerequisite)->GetResolved())); |
| 313 Promise<ThenR>::Resolve(); |
| 314 } |
| 315 |
| 316 void ExecutorDrivenResolve() override { |
| 317 for (const scoped_refptr<PromiseBase>& prerequisite : |
| 318 PromiseBase::prerequisites_) { |
| 319 if (prerequisite->state() == PromiseBase::State::RESOLVED || |
| 320 prerequisite->state() == PromiseBase::State::REJECTED) { |
| 321 ResolveInternal(std::move(prerequisite.get())); |
| 322 return; |
| 323 } |
| 324 } |
| 325 NOTREACHED(); |
| 326 } |
| 327 |
| 328 ~RacePromises() override {} |
| 329 |
| 330 base::Callback<CallbackR(typename AnyPromise::ReturnType)> cb_; |
| 331 }; |
| 332 |
| 333 template <typename ThenR, typename CallbackR> |
| 334 class SCHEDULER_EXPORT RaceVoidPromises final : public Promise<ThenR> { |
| 335 public: |
| 336 RaceVoidPromises(base::Callback<CallbackR()>&& cb, |
| 337 std::vector<scoped_refptr<PromiseBase>>&& promises) |
| 338 : Promise<ThenR>(std::move(promises), |
| 339 PromiseBase::PrerequisitePolicy::ANY), |
| 340 cb_(std::move(cb)) {} |
| 341 |
| 342 private: |
| 343 template <typename CB = CallbackR> |
| 344 enable_if_not_void_t<CB, void> ResolveInternal() { |
| 345 Promise<ThenR>::Resolve(std::move(cb_.Run())); |
| 346 } |
| 347 |
| 348 template <typename CB = CallbackR> |
| 349 enable_if_void_t<CB, void> ResolveInternal() { |
| 350 cb_.Run(); |
| 351 Promise<ThenR>::Resolve(); |
| 352 } |
| 353 |
| 354 void ExecutorDrivenResolve() override { |
| 355 for (const scoped_refptr<PromiseBase>& prerequisite : |
| 356 PromiseBase::prerequisites_) { |
| 357 if (prerequisite->state() == PromiseBase::State::RESOLVED) { |
| 358 ResolveInternal(); |
| 359 return; |
| 360 } |
| 361 } |
| 362 NOTREACHED(); |
| 363 } |
| 364 |
| 365 ~RaceVoidPromises() override {} |
| 366 |
| 367 base::Callback<CallbackR()> cb_; |
| 368 }; |
| 369 |
| 370 template <typename R> |
| 371 class SCHEDULER_EXPORT RaceSpec { |
| 372 public: |
| 373 template <typename RR> |
| 374 static PromiseBase* GetPromiseBase(RR r) { |
| 375 return r.promise(); |
| 376 } |
| 377 |
| 378 template <typename... Promises> |
| 379 RaceSpec(::promise::Promise<R> r, Promises... promises) |
| 380 : promises_({r.promise(), GetPromiseBase(promises)...}) {} |
| 381 |
| 382 template <typename RR = R, typename ThenR> |
| 383 enable_if_not_void_t<RR, ::promise::Promise<ThenR>> Then( |
| 384 base::Callback<ThenR(RR)>&& cb) { |
| 385 return ::promise::Promise<ThenR>(new RacePromises<ThenR, ThenR, Promise<R>>( |
| 386 std::move(cb), std::move(promises_))); |
| 387 } |
| 388 |
| 389 template <typename ThenR> |
| 390 ::promise::Promise<ThenR> Then(base::Callback<ThenR()>&& cb) { |
| 391 return ::promise::Promise<ThenR>(new RaceVoidPromises<ThenR, ThenR>( |
| 392 std::move(cb), std::move(promises_))); |
| 393 } |
| 394 |
| 395 template <typename RR = R, typename ThenR> |
| 396 enable_if_not_void_t<RR, ::promise::Promise<ThenR>> Then( |
| 397 base::Callback<::promise::Promise<ThenR>(RR)>&& cb) { |
| 398 return ::promise::Promise<ThenR>( |
| 399 new RacePromises<ThenR, ::promise::Promise<ThenR>, Promise<RR>>( |
| 400 std::move(cb), std::move(promises_))); |
| 401 } |
| 402 |
| 403 template <typename ThenR> |
| 404 ::promise::Promise<ThenR> Then( |
| 405 base::Callback<::promise::Promise<ThenR>()>&& cb) { |
| 406 return ::promise::Promise<ThenR>( |
| 407 new RaceVoidPromises<ThenR, ::promise::Promise<ThenR>>( |
| 408 std::move(cb), std::move(promises_))); |
| 409 } |
| 410 |
| 411 private: |
| 412 std::vector<scoped_refptr<PromiseBase>> promises_; |
| 413 }; |
| 414 |
| 415 // === promise::All().Then() implementation |
| 416 |
| 417 template <typename ThenR, typename CB, typename... Promises> |
| 418 class SCHEDULER_EXPORT RunAfterAllPromises final : public Promise<ThenR> { |
| 419 public: |
| 420 RunAfterAllPromises(base::Callback<CB>&& cb, |
| 421 std::vector<scoped_refptr<PromiseBase>>&& promises) |
| 422 : Promise<ThenR>(std::move(promises), |
| 423 PromiseBase::PrerequisitePolicy::ALL), |
| 424 cb_(std::move(cb)) {} |
| 425 |
| 426 private: |
| 427 template <size_t... Indices, class... Args> |
| 428 ThenR forward(indices<Indices...>) { |
| 429 // The PromiseResolver is evaluated for each index in the Indices parameter |
| 430 // pack. The trailing '...' is the template magic that makes that work. |
| 431 return cb_.Run(std::move(PromiseResolver<Indices, Promises...>::GetResolved( |
| 432 PromiseBase::prerequisites_))...); |
| 433 } |
| 434 |
| 435 template <size_t... Indices, class... Args> |
| 436 void forward_void(indices<Indices...>) { |
| 437 // The PromiseResolver is evaluated for each index in the Indices parameter |
| 438 // pack. The trailing '...' is the template magic that makes that work. |
| 439 cb_.Run(std::move(PromiseResolver<Indices, Promises...>::GetResolved( |
| 440 PromiseBase::prerequisites_))...); |
| 441 } |
| 442 |
| 443 template <typename ThenRR = ThenR> |
| 444 enable_if_not_void_t<ThenRR, void> ResolveInternal() { |
| 445 using Indices = typename make_indices<sizeof...(Promises)>::type; |
| 446 Promise<ThenRR>::Resolve(std::move(forward(Indices()))); |
| 447 } |
| 448 |
| 449 template <typename ThenRR = ThenR> |
| 450 enable_if_void_t<ThenRR, void> ResolveInternal() { |
| 451 using Indices = typename make_indices<sizeof...(Promises)>::type; |
| 452 forward_void(Indices()); |
| 453 Promise<ThenRR>::Resolve(); |
| 454 } |
| 455 |
| 456 void ExecutorDrivenResolve() override { ResolveInternal(); } |
| 457 |
| 458 ~RunAfterAllPromises() override {} |
| 459 |
| 460 base::Callback<CB> cb_; |
| 461 }; |
| 462 |
| 463 template <typename ThenR, typename CB, typename... Promises> |
| 464 class SCHEDULER_EXPORT RunAfterAllVoidPromises final : public Promise<ThenR> { |
| 465 public: |
| 466 RunAfterAllVoidPromises(base::Callback<CB>&& cb, |
| 467 std::vector<scoped_refptr<PromiseBase>>&& promises) |
| 468 : Promise<ThenR>(std::move(promises), |
| 469 PromiseBase::PrerequisitePolicy::ALL), |
| 470 cb_(std::move(cb)) {} |
| 471 |
| 472 private: |
| 473 template <typename ThenRR = ThenR> |
| 474 enable_if_not_void_t<ThenRR, void> ResolveInternal() { |
| 475 Promise<ThenR>::Resolve(std::move(std::move(cb_.Run()))); |
| 476 } |
| 477 |
| 478 template <typename ThenRR = ThenR> |
| 479 enable_if_void_t<ThenRR, void> ResolveInternal() { |
| 480 cb_.Run(); |
| 481 Promise<ThenR>::Resolve(); |
| 482 } |
| 483 |
| 484 void ExecutorDrivenResolve() override { ResolveInternal(); } |
| 485 |
| 486 ~RunAfterAllVoidPromises() override {} |
| 487 |
| 488 base::Callback<CB> cb_; |
| 489 }; |
| 490 |
| 491 template <typename... Promises> |
| 492 class SCHEDULER_EXPORT AllSpec { |
| 493 public: |
| 494 template <typename R> |
| 495 static PromiseBase* GetPromiseBase(R r) { |
| 496 return r.promise(); |
| 497 } |
| 498 |
| 499 AllSpec(Promises... promises) : promises_({GetPromiseBase(promises)...}) {} |
| 500 |
| 501 template <typename ThenR, typename... ThenArgs> |
| 502 scoped_refptr<Promise<ThenR>> Then(base::Callback<ThenR(ThenArgs...)>&& cb) { |
| 503 static_assert( |
| 504 sizeof...(ThenArgs) == sizeof...(Promises), |
| 505 "Must have the same number of promises and callback arguments"); |
| 506 static_assert(sizeof...(Promises) > 0, |
| 507 "Must have at least one promise to wait on"); |
| 508 return make_scoped_refptr<Promise<ThenR>>( |
| 509 new RunAfterAllPromises<ThenR, ThenR(ThenArgs...), Promises...>( |
| 510 std::move(cb), std::move(promises_))); |
| 511 } |
| 512 |
| 513 template <typename ThenR> |
| 514 scoped_refptr<Promise<ThenR>> Then(base::Callback<ThenR()>&& cb) { |
| 515 static_assert(sizeof...(Promises) > 0, |
| 516 "Must have at least one promise to wait on"); |
| 517 return make_scoped_refptr<Promise<ThenR>>( |
| 518 new RunAfterAllVoidPromises<ThenR, ThenR(), Promises...>( |
| 519 std::move(cb), std::move(promises_))); |
| 520 } |
| 521 |
| 522 private: |
| 523 std::vector<scoped_refptr<PromiseBase>> promises_; |
| 524 }; |
| 525 |
| 526 } // namespace internal |
| 527 } // namespace promise |
| 528 |
| 529 #endif // COMPONENTS_SCHEDULER_PROMISES_PROMISE_INTERNAL_H_ |
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