mirror of https://github.com/poanetwork/gecko.git
59 lines
1.7 KiB
Go
59 lines
1.7 KiB
Go
// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
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// See the file LICENSE for licensing terms.
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package snowball
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import (
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"fmt"
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)
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// binarySnowball is the implementation of a binary snowball instance
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type binarySnowball struct {
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// wrap the binary snowflake logic
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binarySnowflake
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// preference is the choice with the largest number of successful polls.
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// Ties are broken by switching choice lazily
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preference int
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// numSuccessfulPolls tracks the total number of successful network polls of
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// the 0 and 1 choices
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numSuccessfulPolls [2]int
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}
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// Initialize implements the BinarySnowball interface
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func (sb *binarySnowball) Initialize(beta, choice int) {
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sb.binarySnowflake.Initialize(beta, choice)
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sb.preference = choice
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}
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// Preference implements the BinarySnowball interface
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func (sb *binarySnowball) Preference() int {
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// It is possible, with low probability, that the snowflake preference is
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// not equal to the snowball preference when snowflake finalizes. However,
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// this case is handled for completion. Therefore, if snowflake is
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// finalized, then our finalized snowflake choice should be preferred.
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if sb.Finalized() {
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return sb.binarySnowflake.Preference()
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}
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return sb.preference
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}
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// RecordSuccessfulPoll implements the BinarySnowball interface
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func (sb *binarySnowball) RecordSuccessfulPoll(choice int) {
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sb.numSuccessfulPolls[choice]++
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if sb.numSuccessfulPolls[choice] > sb.numSuccessfulPolls[1-choice] {
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sb.preference = choice
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}
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sb.binarySnowflake.RecordSuccessfulPoll(choice)
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}
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func (sb *binarySnowball) String() string {
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return fmt.Sprintf(
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"SB(Preference = %d, NumSuccessfulPolls[0] = %d, NumSuccessfulPolls[1] = %d, %s)",
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sb.preference,
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sb.numSuccessfulPolls[0],
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sb.numSuccessfulPolls[1],
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&sb.binarySnowflake)
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}
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