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69 lines
1.9 KiB
Go
69 lines
1.9 KiB
Go
// GoToSocial
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// Copyright (C) GoToSocial Authors admin@gotosocial.org
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// SPDX-License-Identifier: AGPL-3.0-or-later
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package ffmpeg
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import (
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"context"
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)
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// runner simply abstracts away the complexities
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// of limiting the number of concurrent running
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// instances of a particular WebAssembly module.
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type runner struct{ pool chan struct{} }
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// Init initializes the runner to
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// only allow 'n' concurrently running
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// instances. Special cases include 0
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// which clamps to 1, and < 0 which
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// disables the limit alltogether.
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func (r *runner) Init(n int) {
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// Reset pool.
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r.pool = nil
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// Clamp to 1.
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if n <= 0 {
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n = 1
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}
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// Allocate new pool channel.
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r.pool = make(chan struct{}, n)
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for i := 0; i < n; i++ {
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r.pool <- struct{}{}
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}
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}
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// Run will attempt to pass the given compiled WebAssembly module with args to run(), waiting on
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// the receiving runner until a free slot is available to run an instance, (if a limit is enabled).
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func (r *runner) Run(ctx context.Context, run func() (uint32, error)) (uint32, error) {
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select {
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// Context canceled.
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case <-ctx.Done():
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return 0, ctx.Err()
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// Slot acquired.
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case <-r.pool:
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}
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// Release slot back to pool on end.
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defer func() { r.pool <- struct{}{} }()
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// Call run.
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return run()
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}
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