11// Licensed to the .NET Foundation under one or more agreements.
22// The .NET Foundation licenses this file to you under the MIT license.
33
4+ using System . Diagnostics ;
45using System . IO . Pipes ;
5- using Microsoft . DotNet . Watch ;
66using Microsoft . DotNet . HotReload ;
77
88/// <summary>
99/// The runtime startup hook looks for top-level type named "StartupHook".
1010/// </summary>
1111internal sealed class StartupHook
1212{
13- private static readonly bool s_logToStandardOutput = Environment . GetEnvironmentVariable ( EnvironmentVariables . Names . HotReloadDeltaClientLogMessages ) == "1" ;
14- private static readonly string s_namedPipeName = Environment . GetEnvironmentVariable ( EnvironmentVariables . Names . DotnetWatchHotReloadNamedPipeName ) ;
13+ private const int ConnectionTimeoutMS = 5000 ;
14+
15+ private static readonly bool s_logToStandardOutput = Environment . GetEnvironmentVariable ( AgentEnvironmentVariables . HotReloadDeltaClientLogMessages ) == "1" ;
16+ private static readonly string s_namedPipeName = Environment . GetEnvironmentVariable ( AgentEnvironmentVariables . DotNetWatchHotReloadNamedPipeName ) ;
1517
1618 /// <summary>
1719 /// Invoked by the runtime when the containing assembly is listed in DOTNET_STARTUP_HOOKS.
@@ -22,65 +24,148 @@ public static void Initialize()
2224
2325 Log ( $ "Loaded into process: { processPath } ") ;
2426
25- ClearHotReloadEnvironmentVariables ( ) ;
27+ HotReloadAgent . ClearHotReloadEnvironmentVariables ( typeof ( StartupHook ) ) ;
28+
29+ Log ( $ "Connecting to hot-reload server") ;
2630
27- _ = Task . Run ( async ( ) =>
31+ // Connect to the pipe synchronously.
32+ //
33+ // If a debugger is attached and there is a breakpoint in the startup code connecting asynchronously would
34+ // set up a race between this code connecting to the server, and the breakpoint being hit. If the breakpoint
35+ // hits first, applying changes will throw an error that the client is not connected.
36+ //
37+ // Updates made before the process is launched need to be applied before loading the affected modules.
38+
39+ var pipeClient = new NamedPipeClientStream ( "." , s_namedPipeName , PipeDirection . InOut , PipeOptions . CurrentUserOnly | PipeOptions . Asynchronous ) ;
40+ try
41+ {
42+ pipeClient . Connect ( ConnectionTimeoutMS ) ;
43+ Log ( "Connected." ) ;
44+ }
45+ catch ( TimeoutException )
2846 {
29- Log ( $ "Connecting to hot-reload server") ;
47+ Log ( $ "Failed to connect in { ConnectionTimeoutMS } ms.") ;
48+ return ;
49+ }
3050
31- const int TimeOutMS = 5000 ;
51+ var agent = new HotReloadAgent ( ) ;
52+ try
53+ {
54+ // block until initialization completes:
55+ InitializeAsync ( pipeClient , agent , CancellationToken . None ) . GetAwaiter ( ) . GetResult ( ) ;
3256
33- using var pipeClient = new NamedPipeClientStream ( "." , s_namedPipeName , PipeDirection . InOut , PipeOptions . CurrentUserOnly | PipeOptions . Asynchronous ) ;
34- try
35- {
36- await pipeClient . ConnectAsync ( TimeOutMS ) ;
37- Log ( "Connected." ) ;
38- }
39- catch ( TimeoutException )
40- {
41- Log ( $ "Failed to connect in { TimeOutMS } ms.") ;
42- return ;
43- }
57+ // fire and forget:
58+ _ = ReceiveAndApplyUpdatesAsync ( pipeClient , agent , initialUpdates : false , CancellationToken . None ) ;
59+ }
60+ catch ( Exception ex )
61+ {
62+ Log ( ex . Message ) ;
63+ pipeClient . Dispose ( ) ;
64+ }
65+ }
4466
45- using var agent = new HotReloadAgent ( ) ;
46- try
47- {
48- agent . Reporter . Report ( "Writing capabilities: " + agent . Capabilities , AgentMessageSeverity . Verbose ) ;
67+ private static async ValueTask InitializeAsync ( NamedPipeClientStream pipeClient , HotReloadAgent agent , CancellationToken cancellationToken )
68+ {
69+ agent . Reporter . Report ( "Writing capabilities: " + agent . Capabilities , AgentMessageSeverity . Verbose ) ;
4970
50- var initPayload = new ClientInitializationRequest ( agent . Capabilities ) ;
51- await initPayload . WriteAsync ( pipeClient , CancellationToken . None ) ;
71+ var initPayload = new ClientInitializationResponse ( agent . Capabilities ) ;
72+ await initPayload . WriteAsync ( pipeClient , cancellationToken ) ;
73+
74+ // Apply updates made before this process was launched to avoid executing unupdated versions of the affected modules.
75+ await ReceiveAndApplyUpdatesAsync ( pipeClient , agent , initialUpdates : true , cancellationToken ) ;
76+ }
5277
53- while ( pipeClient . IsConnected )
78+ private static async Task ReceiveAndApplyUpdatesAsync ( NamedPipeClientStream pipeClient , HotReloadAgent agent , bool initialUpdates , CancellationToken cancellationToken )
79+ {
80+ try
81+ {
82+ while ( pipeClient . IsConnected )
83+ {
84+ var payloadType = ( RequestType ) await pipeClient . ReadByteAsync ( cancellationToken ) ;
85+ switch ( payloadType )
5486 {
55- var update = await ManagedCodeUpdateRequest . ReadAsync ( pipeClient , CancellationToken . None ) ;
56- Log ( $ "ResponseLoggingLevel = { update . ResponseLoggingLevel } ") ;
57-
58- bool success ;
59- try
60- {
61- agent . ApplyDeltas ( update . Deltas ) ;
62- success = true ;
63- }
64- catch ( Exception e )
65- {
66- agent . Reporter . Report ( $ "The runtime failed to applying the change: { e . Message } ", AgentMessageSeverity . Error ) ;
67- agent . Reporter . Report ( "Further changes won't be applied to this process." , AgentMessageSeverity . Warning ) ;
68- success = false ;
69- }
70-
71- var logEntries = agent . GetAndClearLogEntries ( update . ResponseLoggingLevel ) ;
72-
73- var response = new UpdateResponse ( logEntries , success ) ;
74- await response . WriteAsync ( pipeClient , CancellationToken . None ) ;
87+ case RequestType . ManagedCodeUpdate :
88+ // Shouldn't get initial managed code updates when the debugger is attached.
89+ // The debugger itself applies these updates when launching process with the debugger attached.
90+ Debug . Assert ( ! Debugger . IsAttached ) ;
91+ await ReadAndApplyManagedCodeUpdateAsync ( pipeClient , agent , cancellationToken ) ;
92+ break ;
93+
94+ case RequestType . StaticAssetUpdate :
95+ await ReadAndApplyStaticAssetUpdateAsync ( pipeClient , agent , cancellationToken ) ;
96+ break ;
97+
98+ case RequestType . InitialUpdatesCompleted when initialUpdates :
99+ return ;
100+
101+ default :
102+ // can't continue, the pipe content is in an unknown state
103+ Log ( $ "Unexpected payload type: { payloadType } . Terminating agent.") ;
104+ return ;
75105 }
76106 }
77- catch ( Exception e )
107+ }
108+ catch ( Exception ex )
109+ {
110+ Log ( ex . Message ) ;
111+ }
112+ finally
113+ {
114+ if ( ! pipeClient . IsConnected )
115+ {
116+ await pipeClient . DisposeAsync ( ) ;
117+ }
118+
119+ if ( ! initialUpdates )
78120 {
79- Log ( e . ToString ( ) ) ;
121+ agent . Dispose ( ) ;
80122 }
123+ }
124+ }
125+
126+ private static async ValueTask ReadAndApplyManagedCodeUpdateAsync (
127+ NamedPipeClientStream pipeClient ,
128+ HotReloadAgent agent ,
129+ CancellationToken cancellationToken )
130+ {
131+ var request = await ManagedCodeUpdateRequest . ReadAsync ( pipeClient , cancellationToken ) ;
81132
82- Log ( "Stopped received delta updates. Server is no longer connected." ) ;
83- } ) ;
133+ bool success ;
134+ try
135+ {
136+ agent . ApplyDeltas ( request . Deltas ) ;
137+ success = true ;
138+ }
139+ catch ( Exception e )
140+ {
141+ agent . Reporter . Report ( $ "The runtime failed to applying the change: { e . Message } ", AgentMessageSeverity . Error ) ;
142+ agent . Reporter . Report ( "Further changes won't be applied to this process." , AgentMessageSeverity . Warning ) ;
143+ success = false ;
144+ }
145+
146+ var logEntries = agent . GetAndClearLogEntries ( request . ResponseLoggingLevel ) ;
147+
148+ var response = new UpdateResponse ( logEntries , success ) ;
149+ await response . WriteAsync ( pipeClient , cancellationToken ) ;
150+ }
151+
152+ private static async ValueTask ReadAndApplyStaticAssetUpdateAsync (
153+ NamedPipeClientStream pipeClient ,
154+ HotReloadAgent agent ,
155+ CancellationToken cancellationToken )
156+ {
157+ var request = await StaticAssetUpdateRequest . ReadAsync ( pipeClient , cancellationToken ) ;
158+
159+ agent . ApplyStaticAssetUpdate ( new StaticAssetUpdate ( request . AssemblyName , request . RelativePath , request . Contents , request . IsApplicationProject ) ) ;
160+
161+ var logEntries = agent . GetAndClearLogEntries ( request . ResponseLoggingLevel ) ;
162+
163+ // Updating static asset only invokes ContentUpdate metadata update handlers.
164+ // Failures of these handlers are reported to the log and ignored.
165+ // Therefore, this request always succeeds.
166+ var response = new UpdateResponse ( logEntries , success : true ) ;
167+
168+ await response . WriteAsync ( pipeClient , cancellationToken ) ;
84169 }
85170
86171 public static bool IsMatchingProcess ( string processPath , string targetProcessPath )
@@ -101,32 +186,6 @@ public static bool IsMatchingProcess(string processPath, string targetProcessPat
101186 string . Equals ( processPath [ ..^ 4 ] , targetProcessPath [ ..^ 4 ] , comparison ) ;
102187 }
103188
104- internal static void ClearHotReloadEnvironmentVariables ( )
105- {
106- // Clear any hot-reload specific environment variables. This prevents child processes from being
107- // affected by the current app's hot reload settings. See https://github.com/dotnet/runtime/issues/58000
108-
109- Environment . SetEnvironmentVariable ( EnvironmentVariables . Names . DotnetStartupHooks ,
110- RemoveCurrentAssembly ( Environment . GetEnvironmentVariable ( EnvironmentVariables . Names . DotnetStartupHooks ) ) ) ;
111-
112- Environment . SetEnvironmentVariable ( EnvironmentVariables . Names . DotnetWatchHotReloadNamedPipeName , "" ) ;
113- Environment . SetEnvironmentVariable ( EnvironmentVariables . Names . HotReloadDeltaClientLogMessages , "" ) ;
114- }
115-
116- internal static string RemoveCurrentAssembly ( string environment )
117- {
118- if ( environment is "" )
119- {
120- return environment ;
121- }
122-
123- var assemblyLocation = typeof ( StartupHook ) . Assembly . Location ;
124- var updatedValues = environment . Split ( Path . PathSeparator , StringSplitOptions . RemoveEmptyEntries )
125- . Where ( e => ! string . Equals ( e , assemblyLocation , StringComparison . OrdinalIgnoreCase ) ) ;
126-
127- return string . Join ( Path . PathSeparator , updatedValues ) ;
128- }
129-
130189 private static void Log ( string message )
131190 {
132191 if ( s_logToStandardOutput )
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