path: root/core/chain_pow.go

// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package core

import (
    "runtime"

    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/pow"
)

// nonceCheckResult contains the result of a nonce verification.
type nonceCheckResult struct {
    index int  // Index of the item verified from an input array
    valid bool // Result of the nonce verification
}

// verifyNoncesFromHeaders starts a concurrent header nonce verification,
// returning a quit channel to abort the operations and a results channel
// to retrieve the async verifications.
func verifyNoncesFromHeaders(checker pow.PoW, headers []*types.Header) (chan<- struct{}, <-chan nonceCheckResult) {
    items := make([]pow.Block, len(headers))
    for i, header := range headers {
        items[i] = types.NewBlockWithHeader(header)
    }
    return verifyNonces(checker, items)
}

// verifyNoncesFromBlocks starts a concurrent block nonce verification,
// returning a quit channel to abort the operations and a results channel
// to retrieve the async verifications.
func verifyNoncesFromBlocks(checker pow.PoW, blocks []*types.Block) (chan<- struct{}, <-chan nonceCheckResult) {
    items := make([]pow.Block, len(blocks))
    for i, block := range blocks {
        items[i] = block
    }
    return verifyNonces(checker, items)
}

// verifyNonces starts a concurrent nonce verification, returning a quit channel
// to abort the operations and a results channel to retrieve the async checks.
func verifyNonces(checker pow.PoW, items []pow.Block) (chan<- struct{}, <-chan nonceCheckResult) {
    // Spawn as many workers as allowed threads
    workers := runtime.GOMAXPROCS(0)
    if len(items) < workers {
        workers = len(items)
    }
    // Create a task channel and spawn the verifiers
    tasks := make(chan int, workers)
    results := make(chan nonceCheckResult, len(items)) // Buffered to make sure all workers stop
    for i := 0; i < workers; i++ {
        go func() {
            for index := range tasks {
                results <- nonceCheckResult{index: index, valid: checker.Verify(items[index])}
            }
        }()
    }
    // Feed item indices to the workers until done or aborted
    abort := make(chan struct{})
    go func() {
        defer close(tasks)

        for i := range items {
            select {
            case tasks <- i:
                continue
            case <-abort:
                return
            }
        }
    }()
    return abort, results
}