| 1 | package websocket
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| 2 |
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| 3 | // CompressionMode represents the modes available to the deflate extension.
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| 4 | // See https://tools.ietf.org/html/rfc7692
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| 5 | //
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| 6 | // A compatibility layer is implemented for the older deflate-frame extension used
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| 7 | // by safari. See https://tools.ietf.org/html/draft-tyoshino-hybi-websocket-perframe-deflate-06
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| 8 | // It will work the same in every way except that we cannot signal to the peer we
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| 9 | // want to use no context takeover on our side, we can only signal that they should.
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| 10 | // It is however currently disabled due to Safari bugs. See https://github.com/nhooyr/websocket/issues/218
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| 11 | type CompressionMode int
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| 12 |
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| 13 | const (
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| 14 | // CompressionNoContextTakeover grabs a new flate.Reader and flate.Writer as needed
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| 15 | // for every message. This applies to both server and client side.
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| 16 | //
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| 17 | // This means less efficient compression as the sliding window from previous messages
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| 18 | // will not be used but the memory overhead will be lower if the connections
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| 19 | // are long lived and seldom used.
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| 20 | //
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| 21 | // The message will only be compressed if greater than 512 bytes.
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| 22 | CompressionNoContextTakeover CompressionMode = iota
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| 23 |
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| 24 | // CompressionContextTakeover uses a flate.Reader and flate.Writer per connection.
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| 25 | // This enables reusing the sliding window from previous messages.
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| 26 | // As most WebSocket protocols are repetitive, this can be very efficient.
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| 27 | // It carries an overhead of 8 kB for every connection compared to CompressionNoContextTakeover.
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| 28 | //
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| 29 | // If the peer negotiates NoContextTakeover on the client or server side, it will be
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| 30 | // used instead as this is required by the RFC.
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| 31 | CompressionContextTakeover
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| 32 |
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| 33 | // CompressionDisabled disables the deflate extension.
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| 34 | //
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| 35 | // Use this if you are using a predominantly binary protocol with very
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| 36 | // little duplication in between messages or CPU and memory are more
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| 37 | // important than bandwidth.
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| 38 | CompressionDisabled
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| 39 | )
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