Cache the deployment flags to improve startup (#340)

* Cache the deployment flags to improve startup

- The deployment flags are cached when calculated as new blocks come in.
- The deployment flags are read from cache at startup, as they cannot have changed since shutdown.
- This gives a very big improvement on node startup.
- #337

* Add empty constructor

- Needed for tests.

* Add null check for integration tests

* Move persisting of flags to BaseFeature

- Check the flags every minute and persist if needed.
- This only validates ScriptFlags, not BIP30/BIP34/LockTimeFlags.

Author: sondreb

src/Blockcore/Base/BaseFeature.cs

@@ -129,6 +129,10 @@ public sealed class BaseFeature : FullNodeFeature
         /// <inheritdoc cref="IPartialValidator"/>
         private readonly IPartialValidator partialValidator;
 
+        private readonly NodeDeployments nodeDeployments;
+
+        private DeploymentFlags deploymentFlags;
+
         public BaseFeature(NodeSettings nodeSettings,
             DataFolder dataFolder,
             INodeLifetime nodeLifetime,
@@ -151,6 +155,7 @@ public BaseFeature(NodeSettings nodeSettings,
             IBlockStore blockStore,
             Network network,
             ITipsManager tipsManager,
+            NodeDeployments nodeDeployments,
             IKeyValueRepository keyValueRepo,
             INodeStats nodeStats,
             IBroadcasterManager broadcasterManager,
@@ -176,6 +181,7 @@ public BaseFeature(NodeSettings nodeSettings,
             this.peerBanning = Guard.NotNull(peerBanning, nameof(peerBanning));
             this.tipsManager = Guard.NotNull(tipsManager, nameof(tipsManager));
             this.keyValueRepo = Guard.NotNull(keyValueRepo, nameof(keyValueRepo));
+            this.nodeDeployments = nodeDeployments;
 
             this.peerAddressManager = Guard.NotNull(peerAddressManager, nameof(peerAddressManager));
             this.peerAddressManager.PeerFilePath = this.dataFolder;
@@ -278,7 +284,21 @@ private async Task StartChainAsync()
                 await this.chainRepository.SaveAsync(this.chainIndexer).ConfigureAwait(false);
 
                 if (this.provenBlockHeaderStore != null)
+                {
                     await this.provenBlockHeaderStore.SaveAsync().ConfigureAwait(false);
+                }
+
+                // Get latest flags (often cached) and persist.
+                var flags = this.nodeDeployments.GetFlags(this.consensusManager.Tip);
+
+                if (this.deploymentFlags == null || flags.ScriptFlags != this.deploymentFlags.ScriptFlags)
+                {
+                    // Update the persistent disk cache of Flags when we retrieve it.
+                    this.keyValueRepo.SaveValueJson("deploymentflags", flags);
+
+                    // Update the local cached copy used to validate against. We don't want to persist to disk unless the flags actually has changed.
+                    this.deploymentFlags = flags;
+                }
             },
             this.nodeLifetime.ApplicationStopping,
             repeatEvery: TimeSpan.FromMinutes(1.0),

src/Features/Blockcore.Features.Consensus/ConsensusFeature.cs

@@ -11,6 +11,7 @@
 using Blockcore.Networks;
 using Blockcore.P2P.Protocol.Payloads;
 using Blockcore.Signals;
+using Blockcore.Utilities.Store;
 using NBitcoin;
 
 [assembly: InternalsVisibleTo("Blockcore.Features.Miner.Tests")]
@@ -30,27 +31,39 @@ public class ConsensusFeature : FullNodeFeature
 
         private readonly NodeDeployments nodeDeployments;
 
+        private readonly IKeyValueRepository keyValueRepository;
+
         public ConsensusFeature(
             Network network,
             IChainState chainState,
             IConnectionManager connectionManager,
             ISignals signals,
             IConsensusManager consensusManager,
-            NodeDeployments nodeDeployments)
+            NodeDeployments nodeDeployments,
+            IKeyValueRepository keyValueRepository)
         {
             this.chainState = chainState;
             this.connectionManager = connectionManager;
             this.signals = signals;
             this.consensusManager = consensusManager;
             this.nodeDeployments = nodeDeployments;
+            this.keyValueRepository = keyValueRepository;
 
             this.chainState.MaxReorgLength = network.Consensus.MaxReorgLength;
         }
 
         /// <inheritdoc />
         public override Task InitializeAsync()
         {
-            DeploymentFlags flags = this.nodeDeployments.GetFlags(this.consensusManager.Tip);
+            DeploymentFlags flags = this.keyValueRepository.LoadValueJson<DeploymentFlags>("deploymentflags");
+
+            if (flags == null)
+            {
+                flags = this.nodeDeployments.GetFlags(this.consensusManager.Tip);
+
+                // Update the cache of Flags when we retrieve it.
+                this.keyValueRepository.SaveValueJson("deploymentflags", flags);
+            }
 
             if (flags.ScriptFlags.HasFlag(ScriptVerify.Witness))
             {

src/Features/Blockcore.Features.Consensus/PosConsensusFeature.cs

@@ -15,6 +15,7 @@
 using Blockcore.Networks;
 using Blockcore.P2P.Peer;
 using Blockcore.Signals;
+using Blockcore.Utilities.Store;
 using Microsoft.Extensions.Logging;
 using NBitcoin;
 
@@ -51,7 +52,9 @@ public PosConsensusFeature(
             ILoggerFactory loggerFactory,
             ICheckpoints checkpoints,
             IProvenBlockHeaderStore provenBlockHeaderStore,
-            ConnectionManagerSettings connectionManagerSettings) : base(network, chainState, connectionManager, signals, consensusManager, nodeDeployments)
+            ConnectionManagerSettings connectionManagerSettings,
+            IKeyValueRepository keyValueRepository
+            ) : base(network, chainState, connectionManager, signals, consensusManager, nodeDeployments, keyValueRepository)
         {
             this.network = network;
             this.chainState = chainState;

src/Features/Blockcore.Features.Consensus/PowConsensusFeature.cs

@@ -9,6 +9,7 @@
 using Blockcore.Interfaces;
 using Blockcore.Networks;
 using Blockcore.Signals;
+using Blockcore.Utilities.Store;
 using Microsoft.Extensions.Logging;
 using NBitcoin;
 
@@ -38,7 +39,8 @@ public PowConsensusFeature(
             IInitialBlockDownloadState initialBlockDownloadState,
             IPeerBanning peerBanning,
             ISignals signals,
-            ILoggerFactory loggerFactory) : base(network, chainState, connectionManager, signals, consensusManager, nodeDeployments)
+            ILoggerFactory loggerFactory,
+            IKeyValueRepository keyValueRepository) : base(network, chainState, connectionManager, signals, consensusManager, nodeDeployments, keyValueRepository)
         {
             this.chainState = chainState;
             this.connectionManager = connectionManager;