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42 lines
1.4 KiB
Go
42 lines
1.4 KiB
Go
// Copyright (c) 2018 Shivaram Lingamneni
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package irc
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import (
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"runtime"
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"github.com/ergochat/ergo/irc/utils"
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)
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// See #237 for context. Operations that might allocate large amounts of temporary
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// garbage, or temporarily tie up some other resource, may cause thrashing unless
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// their concurrency is artificially restricted. We use `chan bool` as a
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// (regrettably, unary-encoded) counting semaphore to enforce these restrictions.
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const (
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// this is a tradeoff between exploiting CPU-level parallelism (higher values better)
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// and not thrashing the allocator (lower values better). really this is all just
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// guesswork. oragono *can* make use of cores beyond this limit --- just not for
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// the protected operations.
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MaxServerSemaphoreCapacity = 32
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)
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// ServerSemaphores includes a named Semaphore corresponding to each concurrency-limited
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// sever operation.
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type ServerSemaphores struct {
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// each distinct operation MUST have its own semaphore;
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// methods that acquire a semaphore MUST NOT call methods that acquire another
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ClientDestroy utils.Semaphore
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IPCheckScript utils.Semaphore
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AuthScript utils.Semaphore
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}
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// Initialize initializes a set of server semaphores.
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func (serversem *ServerSemaphores) Initialize() {
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capacity := runtime.NumCPU()
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if capacity > MaxServerSemaphoreCapacity {
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capacity = MaxServerSemaphoreCapacity
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}
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serversem.ClientDestroy = utils.NewSemaphore(capacity)
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}
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