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Acbox
94 lines
2.9 KiB
Go
94 lines
2.9 KiB
Go
package agent
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import (
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"context"
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"errors"
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"math/rand/v2"
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"net"
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"regexp"
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"strings"
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"time"
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)
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// RetryConfig controls retry behavior for stream failures.
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type RetryConfig struct {
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MaxAttempts int // total retry attempts
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FastAttempts int // first N attempts with no delay
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BaseDelay time.Duration // backoff base for non-fast attempts
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MaxDelay time.Duration // backoff cap
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}
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// err429Pattern matches HTTP 429 status codes in error strings.
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// Requires a non-digit boundary to avoid matching "429" inside larger numbers.
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var err429Pattern = regexp.MustCompile(`(^|[^0-9])429($|[^0-9])`)
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// errEOFPattern matches EOF or connection-level resets.
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var errEOFPattern = regexp.MustCompile(`(?i)connection (reset|refused)|EOF$`)
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// serverErrPattern matches "api error 5XX" where XX is any two digits.
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var serverErrPattern = regexp.MustCompile(`api error 5\d{2}`)
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// DefaultRetryConfig returns the default retry strategy: 10 attempts total,
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// first 5 fast (no delay), last 5 with exponential backoff.
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func DefaultRetryConfig() RetryConfig {
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return RetryConfig{
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MaxAttempts: 10,
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FastAttempts: 5,
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BaseDelay: 1 * time.Second,
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MaxDelay: 30 * time.Second,
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}
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}
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// isRetryableStreamError returns true for errors worth retrying.
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func isRetryableStreamError(err error) bool {
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if err == nil {
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return false
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}
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// Context cancelled/expired — do NOT retry (check first since
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// context.DeadlineExceeded also satisfies net.Error)
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if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
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return false
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}
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// Network-level errors (connection refused, timeout, DNS)
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var netErr net.Error
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if errors.As(err, &netErr) {
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return true
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}
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// HTTP status errors: retry on 429 and 5xx
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errStr := err.Error()
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if err429Pattern.MatchString(errStr) {
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return true
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}
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if strings.Contains(errStr, "rate limit") || strings.Contains(errStr, "rate_limit") {
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return true
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}
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if serverErrPattern.MatchString(errStr) {
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return true
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}
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// Connection reset / EOF
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if errEOFPattern.MatchString(errStr) {
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return true
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}
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return false
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}
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// retryDelay returns the delay before the next retry attempt.
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// For fast attempts (0-indexed < FastAttempts): no delay.
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// For backoff attempts: exponential delay with jitter, capped at MaxDelay.
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func retryDelay(attempt int, cfg RetryConfig) time.Duration {
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if attempt < cfg.FastAttempts {
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return 0
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}
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// Exponential backoff: base * 2^(attempt - fastAttempts), capped to prevent overflow
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backoffIdx := attempt - cfg.FastAttempts
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if backoffIdx > 20 {
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backoffIdx = 20
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}
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delay := cfg.BaseDelay * time.Duration(1<<uint(backoffIdx))
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delay = min(delay, cfg.MaxDelay)
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// Add jitter: random value in [0, delay/2), so final delay is in [delay/2, delay).
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// math/rand is intentional here — cryptographic randomness is not needed for backoff jitter.
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jitter := time.Duration(rand.Int64N(int64(delay / 2))) //nolint:gosec // G404: jitter does not need crypto/rand
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return delay/2 + jitter
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}
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