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feat(enhancement): update godoc, method signature, and cleanup unused…
… symbols. (#936) - add license text
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,3 +1,8 @@ | ||
| // Copyright (c) 2015-present Jeevanandam M ([email protected]), All rights reserved. | ||
| // resty source code and usage is governed by a MIT style | ||
| // license that can be found in the LICENSE file. | ||
| // SPDX-License-Identifier: MIT | ||
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| package resty | ||
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| import ( | ||
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@@ -7,73 +12,92 @@ import ( | |
| "time" | ||
| ) | ||
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| // CircuitBreaker can be in one of three states: Closed, Open, or Half-Open. | ||
| // - When the CircuitBreaker is Closed, requests are allowed to pass through. | ||
| // - If a failure count threshold is reached within a specified time-frame, | ||
| // the CircuitBreaker transitions to the Open state. | ||
| // - When the CircuitBreaker is Open, requests are blocked. | ||
| // - After a specified timeout, the CircuitBreaker transitions to the Half-Open state. | ||
| // - When the CircuitBreaker is Half-Open, a single request is allowed to pass through. | ||
| // - If that request fails, the CircuitBreaker returns to the Open state. | ||
| // - If the number of successes reaches a specified threshold, | ||
| // the CircuitBreaker transitions to the Closed state. | ||
| // CircuitBreaker struct implements a state machine to monitor and manage the | ||
| // states of circuit breakers. The three states are: | ||
| // - Closed: requests are allowed | ||
| // - Open: requests are blocked | ||
| // - Half-Open: a single request is allowed to determine | ||
| // | ||
| // Transitions | ||
| // - To Closed State: when the success count reaches the success threshold. | ||
| // - To Open State: when the failure count reaches the failure threshold. | ||
| // - Half-Open Check: when the specified timeout reaches, a single request is allowed | ||
| // to determine the transition state; if failed, it goes back to the open state. | ||
| type CircuitBreaker struct { | ||
| policies []CircuitBreakerPolicy | ||
| timeout time.Duration | ||
| failThreshold, successThreshold uint32 | ||
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| state atomic.Value // circuitBreakerState | ||
| failCount, successCount atomic.Uint32 | ||
| lastFail time.Time | ||
| policies []CircuitBreakerPolicy | ||
| timeout time.Duration | ||
| failureThreshold uint32 | ||
| successThreshold uint32 | ||
| state atomic.Value // circuitBreakerState | ||
| failureCount atomic.Uint32 | ||
| successCount atomic.Uint32 | ||
| lastFailureAt time.Time | ||
| } | ||
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| // NewCircuitBreaker creates a new [CircuitBreaker] with default settings. | ||
| // NewCircuitBreaker method creates a new [CircuitBreaker] with default settings. | ||
| // | ||
| // The default settings are: | ||
| // - Timeout: 10 seconds | ||
| // - FailThreshold: 3 | ||
| // - SuccessThreshold: 1 | ||
| // - Policies: CircuitBreaker5xxPolicy | ||
| // - Timeout: 10 seconds | ||
| // - FailThreshold: 3 | ||
| // - SuccessThreshold: 1 | ||
| // - Policies: CircuitBreaker5xxPolicy | ||
| func NewCircuitBreaker() *CircuitBreaker { | ||
| cb := &CircuitBreaker{ | ||
| policies: []CircuitBreakerPolicy{CircuitBreaker5xxPolicy}, | ||
| timeout: 10 * time.Second, | ||
| failThreshold: 3, | ||
| failureThreshold: 3, | ||
| successThreshold: 1, | ||
| } | ||
| cb.state.Store(circuitBreakerStateClosed) | ||
| return cb | ||
| } | ||
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| // SetPolicies sets the CircuitBreakerPolicy's that the [CircuitBreaker] will use to determine whether a response is a failure. | ||
| func (cb *CircuitBreaker) SetPolicies(policies []CircuitBreakerPolicy) *CircuitBreaker { | ||
| // SetPolicies method sets the one or more given CircuitBreakerPolicy(s) into | ||
| // [CircuitBreaker], which will be used to determine whether a request is failed | ||
| // or successful by evaluating the response instance. | ||
| // | ||
| // // set one policy | ||
| // cb.SetPolicies(CircuitBreaker5xxPolicy) | ||
| // | ||
| // // set multiple polices | ||
| // cb.SetPolicies(policy1, policy2, policy3) | ||
| // | ||
| // // if you have slice, do | ||
| // cb.SetPolicies(policies...) | ||
| // | ||
| // NOTE: This method overwrites the policies with the given new ones. See [CircuitBreaker.AddPolicies] | ||
| func (cb *CircuitBreaker) SetPolicies(policies ...CircuitBreakerPolicy) *CircuitBreaker { | ||
| cb.policies = policies | ||
| return cb | ||
| } | ||
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| // SetTimeout sets the timeout duration for the [CircuitBreaker]. | ||
| // SetTimeout method sets the timeout duration for the [CircuitBreaker]. When the | ||
| // timeout reaches, a single request is allowed to determine the state. | ||
| func (cb *CircuitBreaker) SetTimeout(timeout time.Duration) *CircuitBreaker { | ||
| cb.timeout = timeout | ||
| return cb | ||
| } | ||
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| // SetFailThreshold sets the number of failures that must occur within the timeout duration for the [CircuitBreaker] to | ||
| // transition to the Open state. | ||
| func (cb *CircuitBreaker) SetFailThreshold(threshold uint32) *CircuitBreaker { | ||
| cb.failThreshold = threshold | ||
| // SetFailureThreshold method sets the number of failures that must occur within the | ||
| // timeout duration for the [CircuitBreaker] to transition to the Open state. | ||
| func (cb *CircuitBreaker) SetFailureThreshold(threshold uint32) *CircuitBreaker { | ||
| cb.failureThreshold = threshold | ||
| return cb | ||
| } | ||
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| // SetSuccessThreshold sets the number of successes that must occur to transition the [CircuitBreaker] from the Half-Open state | ||
| // to the Closed state. | ||
| // SetSuccessThreshold method sets the number of successes that must occur to transition | ||
| // the [CircuitBreaker] from the Half-Open state to the Closed state. | ||
| func (cb *CircuitBreaker) SetSuccessThreshold(threshold uint32) *CircuitBreaker { | ||
| cb.successThreshold = threshold | ||
| return cb | ||
| } | ||
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| // CircuitBreakerPolicy is a function that determines whether a response should trip the [CircuitBreaker]. | ||
| // CircuitBreakerPolicy is a function type that determines whether a response should | ||
| // trip the [CircuitBreaker]. | ||
| type CircuitBreakerPolicy func(resp *http.Response) bool | ||
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| // CircuitBreaker5xxPolicy is a [CircuitBreakerPolicy] that trips the [CircuitBreaker] if the response status code is 500 or greater. | ||
| // CircuitBreaker5xxPolicy is a [CircuitBreakerPolicy] that trips the [CircuitBreaker] if | ||
| // the response status code is 500 or greater. | ||
| func CircuitBreaker5xxPolicy(resp *http.Response) bool { | ||
| return resp.StatusCode > 499 | ||
| } | ||
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@@ -118,17 +142,17 @@ func (cb *CircuitBreaker) applyPolicies(resp *http.Response) { | |
| } | ||
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| if failed { | ||
| if cb.failCount.Load() > 0 && time.Since(cb.lastFail) > cb.timeout { | ||
| cb.failCount.Store(0) | ||
| if cb.failureCount.Load() > 0 && time.Since(cb.lastFailureAt) > cb.timeout { | ||
| cb.failureCount.Store(0) | ||
| } | ||
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| switch cb.getState() { | ||
| case circuitBreakerStateClosed: | ||
| failCount := cb.failCount.Add(1) | ||
| if failCount >= cb.failThreshold { | ||
| failCount := cb.failureCount.Add(1) | ||
| if failCount >= cb.failureThreshold { | ||
| cb.open() | ||
| } else { | ||
| cb.lastFail = time.Now() | ||
| cb.lastFailureAt = time.Now() | ||
| } | ||
| case circuitBreakerStateHalfOpen: | ||
| cb.open() | ||
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@@ -144,8 +168,6 @@ func (cb *CircuitBreaker) applyPolicies(resp *http.Response) { | |
| } | ||
| } | ||
| } | ||
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| return | ||
| } | ||
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| func (cb *CircuitBreaker) open() { | ||
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@@ -157,7 +179,7 @@ func (cb *CircuitBreaker) open() { | |
| } | ||
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| func (cb *CircuitBreaker) changeState(state circuitBreakerState) { | ||
| cb.failCount.Store(0) | ||
| cb.failureCount.Store(0) | ||
| cb.successCount.Store(0) | ||
| cb.state.Store(state) | ||
| } | ||
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