(self: TxReentrantLock): Effect.Effect<number>Acquires a read lock. Blocks if another fiber holds the write lock. If the current fiber already holds the write lock, the read lock is granted (reentrancy). Returns the current number of read locks held by this fiber.
Example (Acquiring a read lock)
import { Effect, TxReentrantLock } from "effect"
const program = Effect.gen(function*() {
const lock = yield* TxReentrantLock.make()
const count = yield* TxReentrantLock.acquireRead(lock)
console.log(count) // 1
yield* TxReentrantLock.releaseRead(lock)
})mutations
Source effect/TxReentrantLock.ts:14121 lines
export const const acquireRead: (
self: TxReentrantLock
) => Effect.Effect<number>
Acquires a read lock. Blocks if another fiber holds the write lock.
If the current fiber already holds the write lock, the read lock is granted (reentrancy).
Returns the current number of read locks held by this fiber.
Example (Acquiring a read lock)
import { Effect, TxReentrantLock } from "effect"
const program = Effect.gen(function*() {
const lock = yield* TxReentrantLock.make()
const count = yield* TxReentrantLock.acquireRead(lock)
console.log(count) // 1
yield* TxReentrantLock.releaseRead(lock)
})
acquireRead = (self: TxReentrantLock(parameter) self: {
stateRef: TxRef.TxRef<LockState>;
toString: () => string;
toJSON: () => unknown;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<number> =>
import EffectEffect.const withFiber: <
A,
E = never,
R = never
>(
evaluate: (
fiber: Fiber<unknown, unknown>
) => Effect<A, E, R>
) => Effect<A, E, R>
Provides access to the current fiber within an effect computation.
Example (Reading the current fiber)
import { Effect } from "effect"
const program = Effect.withFiber((fiber) =>
Effect.succeed(`Fiber ID: ${fiber.id}`)
)
Effect.runPromise(program).then(console.log)
// Output: Fiber ID: 1
withFiber((fiber: Fiber<unknown, unknown>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
import EffectEffect.const gen: {
<Eff extends Effect<any, any, any>, AEff>(
f: () => Generator<Eff, AEff, never>
): Effect<
AEff,
[Eff] extends [never]
? never
: [Eff] extends [
Effect<infer _A, infer E, infer _R>
]
? E
: never,
[Eff] extends [never]
? never
: [Eff] extends [
Effect<infer _A, infer _E, infer R>
]
? R
: never
>
<Self, Eff extends Effect<any, any, any>, AEff>(
options: { readonly self: Self },
f: (this: Self) => Generator<Eff, AEff, never>
): Effect<
AEff,
[Eff] extends [never]
? never
: [Eff] extends [
Effect<infer _A, infer E, infer _R>
]
? E
: never,
[Eff] extends [never]
? never
: [Eff] extends [
Effect<infer _A, infer _E, infer R>
]
? R
: never
>
}
const state: LockStateconst state: {
readers: HashMap.HashMap<number, number>;
writer: Option.Option<readonly [fiberId: number, count: number]>;
}
import TxRefTxRef.const get: <A>(
self: TxRef<A>
) => Effect.Effect<A>
Reads the current value of the TxRef.
When to use
Use to read the current value of a TxRef.
Example (Reading transactional references)
import { Effect, TxRef } from "effect"
const program = Effect.gen(function*() {
const counter = yield* TxRef.make(42)
// Read the value within a transaction
const value = yield* Effect.tx(
TxRef.get(counter)
)
console.log(value) // 42
})
get(self: TxReentrantLock(parameter) self: {
stateRef: TxRef.TxRef<LockState>;
toString: () => string;
toJSON: () => unknown;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
TxReentrantLock.stateRef: TxRef.TxRef<LockState>(property) TxReentrantLock.stateRef: {
version: number;
pending: Map<unknown, () => void>;
value: A;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
const fiberId: numberfiberId = fiber: Fiber<unknown, unknown>(parameter) fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
Fiber<out A, out E = never>.id: numberid
// If another fiber holds the write lock, retry
if (import OptionOption.const isSome: <A>(
self: Option<A>
) => self is Some<A>
Checks whether an Option contains a value (Some).
When to use
Use when you need to branch on a present Option before accessing .value.
Details
- Acts as a type guard, narrowing to
Some<A>
Example (Checking for Some)
import { Option } from "effect"
console.log(Option.isSome(Option.some(1)))
// Output: true
console.log(Option.isSome(Option.none()))
// Output: false
isSome(const state: LockStateconst state: {
readers: HashMap.HashMap<number, number>;
writer: Option.Option<readonly [fiberId: number, count: number]>;
}
LockState.writer: Option.Option<readonly [fiberId: number, count: number]>writer) && const state: LockStateconst state: {
readers: HashMap.HashMap<number, number>;
writer: Option.Option<readonly [fiberId: number, count: number]>;
}
LockState.writer: Option.Option<readonly [fiberId: number, count: number]>(property) LockState.writer: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: A;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Some<readonly [fiberId: number, count: number]>.value: readonly [fiberId: number, count: number](property) Some<readonly [fiberId: number, count: number]>.value: {
0: number;
1: number;
length: 2;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
concat: { (...items: Array<ConcatArray<number>>): Array<number>; (...items: Array<number | ConcatArray<number>>): Array<number> };
join: (separator?: string) => string;
slice: (start?: number, end?: number) => Array<number>;
indexOf: (searchElement: number, fromIndex?: number) => number;
lastIndexOf: (searchElement: number, fromIndex?: number) => number;
every: { (predicate: (value: number, index: number, array: ReadonlyArray<number>) => value is S, thisArg?: any): this is readonly S[]; (predicate: (value: number, index: number, array: ReadonlyArray<number>) => unknown, thisArg?: any): boolean };
some: (predicate: (value: number, index: number, array: ReadonlyArray<number>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: number, index: number, array: ReadonlyArray<number>) => void, thisArg?: any) => void;
map: (callbackfn: (value: number, index: number, array: ReadonlyArray<number>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: number, index: number, array: ReadonlyArray<number>) => value is S, thisArg?: any): Array<S>; (predicate: (value: number, index: number, array: ReadonlyArray<number>) => unknown, thisArg?: any): Array<number> };
reduce: { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: ReadonlyArray<number>) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: ReadonlyArray<numb…;
reduceRight: { (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: ReadonlyArray<number>) => number): number; (callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: ReadonlyArray<numb…;
find: { (predicate: (value: number, index: number, obj: ReadonlyArray<number>) => value is S, thisArg?: any): S | undefined; (predicate: (value: number, index: number, obj: ReadonlyArray<number>) => unknown, thisArg?: any): number | undefined };
findIndex: (predicate: (value: number, index: number, obj: ReadonlyArray<number>) => unknown, thisArg?: any) => number;
entries: () => ArrayIterator<[number, number]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<number>;
includes: (searchElement: number, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: number, index: number, array: Array<number>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => number | undefined;
findLast: { (predicate: (value: number, index: number, array: ReadonlyArray<number>) => value is S, thisArg?: any): S | undefined; (predicate: (value: number, index: number, array: ReadonlyArray<number>) => unknown, thisArg?: any): number | undefine…;
findLastIndex: (predicate: (value: number, index: number, array: ReadonlyArray<number>) => unknown, thisArg?: any) => number;
toReversed: () => Array<number>;
toSorted: (compareFn?: ((a: number, b: number) => number) | undefined) => Array<number>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<number>): Array<number>; (start: number, deleteCount?: number): Array<number> };
with: (index: number, value: number) => Array<number>;
}
const fiberId: numberfiberId) {
return yield* import EffectEffect.const txRetry: Effect<
never,
never,
Transaction
>
const txRetry: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Retries the current transaction by signaling that it must be retried.
Details
NOTE: the transaction retries on any change to transactional values (i.e. TxRef) accessed in its body.
Example (Retrying transactions)
import { Effect, TxRef } from "effect"
const program = Effect.gen(function*() {
// create a transactional reference
const ref = yield* TxRef.make(0)
// forks a fiber that increases the value of `ref` every 100 millis
yield* Effect.forkChild(Effect.forever(
// update to transactional value
Effect.tx(TxRef.update(ref, (n) => n + 1)).pipe(Effect.delay("100 millis"))
))
// the following will retry 10 times until the `ref` value is 10
yield* Effect.tx(Effect.gen(function*() {
const value = yield* TxRef.get(ref)
if (value < 10) {
yield* Effect.log(`retry due to value: ${value}`)
return yield* Effect.txRetry
}
yield* Effect.log(`transaction done with value: ${value}`)
}))
})
Effect.runPromise(program).catch(console.error)
txRetry
}
// Grant read lock
const const currentCount: numbercurrentCount = import OptionOption.const getOrElse: {
<B>(onNone: LazyArg<B>): <A>(
self: Option<A>
) => B | A
<A, B>(self: Option<A>, onNone: LazyArg<B>):
| A
| B
}
import HashMapHashMap.const get: {
<K1 extends K, K>(key: K1): <V>(
self: HashMap<K, V>
) => Option<V>
<K1 extends K, K, V>(
self: HashMap<K, V>,
key: K1
): Option<V>
}
const state: LockStateconst state: {
readers: HashMap.HashMap<number, number>;
writer: Option.Option<readonly [fiberId: number, count: number]>;
}
LockState.readers: HashMap.HashMap<number, number>(property) LockState.readers: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
const fiberId: numberfiberId), () => 0)
const const newCount: numbernewCount = const currentCount: numbercurrentCount + 1
yield* import TxRefTxRef.const set: {
<A>(value: A): (
self: TxRef<A>
) => Effect.Effect<void>
<A>(
self: TxRef<A>,
value: A
): Effect.Effect<void>
}
self: TxReentrantLock(parameter) self: {
stateRef: TxRef.TxRef<LockState>;
toString: () => string;
toJSON: () => unknown;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
TxReentrantLock.stateRef: TxRef.TxRef<LockState>(property) TxReentrantLock.stateRef: {
version: number;
pending: Map<unknown, () => void>;
value: A;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
const state: LockStateconst state: {
readers: HashMap.HashMap<number, number>;
writer: Option.Option<readonly [fiberId: number, count: number]>;
}
LockState.readers: HashMap.HashMap<number, number>(property) LockState.readers: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
import HashMapHashMap.const set: {
<K, V>(key: K, value: V): (
self: HashMap<K, V>
) => HashMap<K, V>
<K, V>(
self: HashMap<K, V>,
key: K,
value: V
): HashMap<K, V>
}
const state: LockStateconst state: {
readers: HashMap.HashMap<number, number>;
writer: Option.Option<readonly [fiberId: number, count: number]>;
}
LockState.readers: HashMap.HashMap<number, number>(property) LockState.readers: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
const fiberId: numberfiberId, const newCount: numbernewCount)
})
return const newCount: numbernewCount
}).Pipeable.pipe<Effect.Effect<number, never, Effect.Transaction>, Effect.Effect<number, never, never>>(this: Effect.Effect<number, never, Effect.Transaction>, ab: (_: Effect.Effect<number, never, Effect.Transaction>) => Effect.Effect<number, never, never>): Effect.Effect<number, never, never> (+21 overloads)pipe(import EffectEffect.const tx: <A, E, R>(
effect: Effect<A, E, R>
) => Effect<A, E, Exclude<R, Transaction>>
Defines a transaction boundary. Transactions are "all or nothing" with respect to changes
made to transactional values (i.e. TxRef) that occur within the transaction body.
Details
If called inside an active transaction, tx composes with the current transaction and reuses
its journal and retry state instead of creating a nested boundary.
Effect transactions are optimistic with retry. A transaction is retried when
its body explicitly calls Effect.txRetry and any accessed transactional
value changes, or when any accessed transactional value changes because a
different transaction commits before the current one.
The outermost tx call creates the transaction boundary and commits or rolls back the full
composed transaction.
Example (Running a transaction)
import { Effect, TxRef } from "effect"
const program = Effect.gen(function*() {
const ref1 = yield* TxRef.make(0)
const ref2 = yield* TxRef.make(0)
// Nested tx calls compose into the same transaction
yield* Effect.tx(Effect.gen(function*() {
yield* TxRef.set(ref1, 10)
yield* Effect.tx(TxRef.set(ref2, 20))
const sum = (yield* TxRef.get(ref1)) + (yield* TxRef.get(ref2))
console.log(`Transaction sum: ${sum}`)
}))
console.log(`Final ref1: ${yield* TxRef.get(ref1)}`) // 10
console.log(`Final ref2: ${yield* TxRef.get(ref2)}`) // 20
})
tx)
)Referenced by 2 symbols