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core: Make topological sort more efficient

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This commit is contained in:
Andras Slemmer 2016-09-08 10:04:18 +01:00
parent d6f82637ad
commit 5596ced5c3
1 changed files with 15 additions and 19 deletions
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34
core/src/main/kotlin/com/r3corda/protocols/ResolveTransactionsProtocol.kt
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@ -33,40 +33,36 @@ class ResolveTransactionsProtocol(private val txHashes: Set<SecureHash>,
companion object {
private fun dependencyIDs(wtx: WireTransaction) = wtx.inputs.map { it.txhash }.toSet()
private fun topologicalSort(transactions: Iterable<SignedTransaction>): List<SignedTransaction> {
private fun topologicalSort(transactions: Collection<SignedTransaction>): List<SignedTransaction> {
// Construct txhash -> dependent-txhashes map
val forwardGraph = HashMap<SecureHash, HashSet<SecureHash>>()
val forwardGraph = HashMap<SecureHash, HashSet<SignedTransaction>>()
transactions.forEach { tx ->
tx.tx.inputs.forEach { input ->
forwardGraph.getOrPut(input.txhash) { HashSet() }.add(tx.id)
forwardGraph.getOrPut(input.txhash) { HashSet() }.add(tx)
}
}
// Construct txhash -> tx map
val transactionMap = HashMap<SecureHash, SignedTransaction>()
transactions.forEach { transactionMap[it.tx.id] = it }
val visited = HashSet<SecureHash>(transactions.size)
val result = ArrayList<SignedTransaction>(transactions.size)
val visited = HashSet<SecureHash>()
val result = LinkedList<SignedTransaction>()
fun visit(transactionHash: SecureHash) {
if (transactionHash in visited) {
fun visit(transaction: SignedTransaction) {
if (transaction.id in visited) {
return
}
visited.add(transactionHash)
forwardGraph[transactionHash]?.forEach {
visited.add(transaction.id)
forwardGraph[transaction.id]?.forEach {
visit(it)
}
result.addFirst(transactionMap[transactionHash]!!)
result.add(transaction)
}
transactions.forEach {
visit(it.tx.id)
visit(it)
}
require(result.size == transactionMap.size)
require(visited.size == transactionMap.size)
require(result.size == transactions.size)
result.reverse()
return result
}
@ -134,7 +130,7 @@ class ResolveTransactionsProtocol(private val txHashes: Set<SecureHash>,
override val topic: String get() = throw UnsupportedOperationException()
@Suspendable
private fun downloadDependencies(depsToCheck: Set<SecureHash>): List<SignedTransaction> {
private fun downloadDependencies(depsToCheck: Set<SecureHash>): Collection<SignedTransaction> {
// Maintain a work queue of all hashes to load/download, initialised with our starting set. Then do a breadth
// first traversal across the dependency graph.
//
@ -184,7 +180,7 @@ class ResolveTransactionsProtocol(private val txHashes: Set<SecureHash>,
throw ExcessivelyLargeTransactionGraph()
}
return resultQ.values.reversed()
return resultQ.values
}
/**