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Another chapter in the never-ending AppDomain security saga. If a computer goes to sleep while SourceGen is running with a project open, life gets confusing when the system wakes up. The keep-alive timer fires and a ping is sent to the remote AppDomain, successfully. At the same time, the lease expires on the remote side, and the objects are discarded (apparently without bothering to query the ILease object). This failure mode is 100% repeatable. Since we can't prevent sandbox objects from disappearing, we have to detect and recover from the problem. Fortunately we don't keep any necessary state on the plugin side, so we can just tear the whole thing down and recreate it. The various methods in ScriptManager now do a "health check" before making calls into the plugin AppDomain. If the ping attempt fails, the AppDomain is "rebooted" by destroying it and creating a new one, reloading all plugins that were in there before. The plugin binaries *should* still be in the PluginDllCache directory since the ping failure was due to objects being discarded, not AppDomain shutdown, and Windows doesn't let you mess with files that hold executable code. A new "reboot security sandbox" option has been added to the DEBUG menu to facilitate testing. The PluginManager's Ping() method gets called more often, but not to the extent that performance will be affected. This change also adds a finalizer to DisasmProject, since we're relying on it to shut down the ScriptManager, and it's relying on callers to invoke its cleanup function. The finalizer throws an assertion if the cleanup function doesn't get called. (Issue #82)
268 lines
11 KiB
C#
268 lines
11 KiB
C#
/*
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* Copyright 2018 faddenSoft
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Linq;
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using System.Reflection;
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using System.Threading;
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using CommonUtil;
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namespace PluginCommon {
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/// <summary>
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/// Manages loaded plugins, in the "remote" AppDomain.
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/// </summary>
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public sealed class PluginManager : MarshalByRefObject {
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/// <summary>
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/// Collection of instances of active plugins, keyed by script identifier. Other
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/// plugin assemblies may be present in the AppDomain, but have not been identified
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/// by the application as being of interest.
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/// </summary>
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private Dictionary<string, IPlugin> mActivePlugins = new Dictionary<string, IPlugin>();
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/// <summary>
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/// Reference to file data.
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/// </summary>
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private byte[] mFileData;
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private DateTime mLastPing;
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/// <summary>
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/// Constructor, invoked from CreateInstanceAndUnwrap().
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/// </summary>
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public PluginManager() {
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Debug.WriteLine("PluginManager ctor (id=" + AppDomain.CurrentDomain.Id + ")");
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mLastPing = DateTime.Now;
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// Seems to require [SecurityCritical]
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//Type lsc = Type.GetType("System.Runtime.Remoting.Lifetime.LifetimeServices");
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//PropertyInfo prop = lsc.GetProperty("LeaseTime");
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//prop.SetValue(null, TimeSpan.FromSeconds(30));
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}
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~PluginManager() {
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Debug.WriteLine("~PluginManager (id=" + AppDomain.CurrentDomain.Id + ")");
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}
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/// <summary>
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/// Sets the file data to use for all plugins.
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///
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/// The file data argument will be an AppDomain-local copy of the data, made by the
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/// argument marshalling code. So plugins can scribble all over it without trashing
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/// the original. We want to store it in PluginManager so we don't make a new copy
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/// for each individual plugin.
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/// </summary>
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/// <param name="fileData">65xx code and data.</param>
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public void SetFileData(byte[] fileData) {
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mFileData = fileData;
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}
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/// <summary>
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/// Tests simple round-trip communication. This may be called from an arbitrary thread.
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/// </summary>
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/// <remarks>
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/// This is used for keep-alives and health checks, so it may be called frequently.
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/// </remarks>
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public int Ping(int val) {
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//Debug.WriteLine("PluginManager Ping tid=" + Thread.CurrentThread.ManagedThreadId +
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// " (id=" + AppDomain.CurrentDomain.Id + "): " + val);
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int result = (int)(DateTime.Now - mLastPing).TotalSeconds;
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mLastPing = DateTime.Now;
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return result;
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}
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/// <summary>
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/// Creates a plugin instance from a compiled assembly. Pass in the script identifier
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/// for future lookups. If the plugin has already been instantiated, that object
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/// will be returned.
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/// </summary>
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/// <param name="dllPath">Full path to compiled assembly.</param>
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/// <param name="scriptIdent">Identifier to use in e.g. GetPlugin().</param>
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/// <returns>Reference to plugin instance.</returns>
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public IPlugin LoadPlugin(string dllPath, string scriptIdent, out string failMsg) {
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if (mActivePlugins.TryGetValue(dllPath, out IPlugin ip)) {
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Debug.WriteLine("PM: returning cached plugin for " + dllPath);
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failMsg = string.Empty;
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return ip;
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}
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Assembly asm = Assembly.LoadFile(dllPath);
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foreach (Type type in asm.GetExportedTypes()) {
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// Using a System.Linq extension method.
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if (type.IsClass && !type.IsAbstract &&
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type.GetInterfaces().Contains(typeof(IPlugin))) {
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ConstructorInfo ctor = type.GetConstructor(Type.EmptyTypes);
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IPlugin iplugin;
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try {
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iplugin = (IPlugin)ctor.Invoke(null);
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} catch (Exception ex) {
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if (ex.InnerException != null) {
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failMsg = ex.InnerException.Message;
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} else {
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failMsg = ex.Message;
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}
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Debug.WriteLine("LoadPlugin: failed to load '" + scriptIdent + "': "
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+ failMsg);
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return null;
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}
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Debug.WriteLine("PM created instance: " + iplugin);
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mActivePlugins.Add(scriptIdent, iplugin);
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failMsg = string.Empty;
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return iplugin;
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}
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}
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throw new Exception("No IPlugin class found in " + dllPath);
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}
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/// <summary>
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/// Gets an instance of a previously-loaded plugin.
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/// </summary>
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/// <param name="scriptIdent">Script identifier that was passed to LoadPlugin().</param>
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/// <returns>Reference to instance of plugin.</returns>
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public IPlugin GetPlugin(string scriptIdent) {
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if (mActivePlugins.TryGetValue(scriptIdent, out IPlugin plugin)) {
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return plugin;
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}
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return null;
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}
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/// <summary>
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/// Returns a string with the assembly's location.
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/// </summary>
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public string GetPluginAssemblyLocation(IPlugin plugin) {
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return plugin.GetType().Assembly.Location;
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}
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/// <summary>
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/// Generates a list of references to instances of active plugins.
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/// </summary>
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/// <returns>Newly-created list of plugin references.</returns>
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public Dictionary<string, IPlugin> GetActivePlugins() {
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Dictionary<string, IPlugin> dict =
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new Dictionary<string, IPlugin>(mActivePlugins.Count);
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foreach (KeyValuePair<string, IPlugin> kvp in mActivePlugins) {
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// copy the contents; probably not necessary across AppDomain
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dict.Add(kvp.Key, kvp.Value);
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}
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Debug.WriteLine("PluginManager: returning " + dict.Count + " plugins (id=" +
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AppDomain.CurrentDomain.Id + ")");
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return dict;
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}
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/// <summary>
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/// Clears the list of loaded plugins. This does not unload the assemblies from
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/// the AppDomain.
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/// </summary>
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public void ClearPluginList() {
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mActivePlugins.Clear();
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}
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/// <summary>
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/// Invokes the Prepare() method on all active plugins.
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/// </summary>
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/// <param name="appRef">Reference to host object providing app services.</param>
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/// <param name="addrEntries">Serialized AddressMap entries.</param>
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/// <param name="plSyms">SymbolTable contents, converted to PlSymbol.</param>
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public void PreparePlugins(IApplication appRef,
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List<AddressMap.AddressMapEntry> addrEntries, List<PlSymbol> plSyms) {
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AddressMap addrMap = new AddressMap(addrEntries);
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AddressTranslate addrTrans = new AddressTranslate(addrMap);
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foreach (KeyValuePair<string, IPlugin> kvp in mActivePlugins) {
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IPlugin ipl = kvp.Value;
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ipl.Prepare(appRef, mFileData, addrTrans);
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if (ipl is IPlugin_SymbolList) {
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((IPlugin_SymbolList)ipl).UpdateSymbolList(plSyms);
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}
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}
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}
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/// <summary>
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/// Invokes the Unprepare() method on all active plugins.
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/// </summary>
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public void UnpreparePlugins() {
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foreach (KeyValuePair<string, IPlugin> kvp in mActivePlugins) {
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IPlugin ipl = kvp.Value;
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ipl.Unprepare();
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}
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}
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/// <summary>
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/// Returns true if any of the plugins report that the before or after label is
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/// significant.
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/// </summary>
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public bool IsLabelSignificant(string labelBefore, string labelAfter) {
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foreach (KeyValuePair<string, IPlugin> kvp in mActivePlugins) {
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IPlugin ipl = kvp.Value;
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if (ipl is IPlugin_SymbolList &&
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((IPlugin_SymbolList)ipl).IsLabelSignificant(labelBefore,
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labelAfter)) {
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return true;
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}
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}
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return false;
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}
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#if false
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/// <summary>
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/// DEBUG ONLY: establish a fast lease timeout. Normally the lease
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/// is five minutes; this reduces it to a few seconds. (The actual time is
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/// also affected by LifetimeServices.LeaseManagerPollTime, which defaults
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/// to 10 seconds.)
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///
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/// Unfortunately this must be tagged [SecurityCritical] to match the method being
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/// overridden, but in a partially-trusted sandbox that's not allowed. You have
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/// to relax security entirely for this to work.
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/// </summary>
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//[SecurityPermissionAttribute(SecurityAction.Demand,
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// Flags = SecurityPermissionFlag.Infrastructure)]
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[System.Security.SecurityCritical]
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public override object InitializeLifetimeService() {
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object lease = base.InitializeLifetimeService();
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// netstandard2.0 doesn't have System.Runtime.Remoting.Lifetime, so use reflection
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PropertyInfo leaseState = lease.GetType().GetProperty("CurrentState");
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PropertyInfo initialLeaseTime = lease.GetType().GetProperty("InitialLeaseTime");
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PropertyInfo sponsorshipTimeout = lease.GetType().GetProperty("SponsorshipTimeout");
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PropertyInfo renewOnCallTime = lease.GetType().GetProperty("RenewOnCallTime");
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Console.WriteLine("Default lease: ini=" +
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initialLeaseTime.GetValue(lease) + " spon=" +
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sponsorshipTimeout.GetValue(lease) + " renOC=" +
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renewOnCallTime.GetValue(lease));
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if ((int)leaseState.GetValue(lease) == 1 /*LeaseState.Initial*/) {
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// Initial lease duration.
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initialLeaseTime.SetValue(lease, TimeSpan.FromSeconds(8));
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// How long we will wait for the sponsor to respond
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// with a lease renewal time.
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sponsorshipTimeout.SetValue(lease, TimeSpan.FromSeconds(5));
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// Each call to the remote object extends the lease so that
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// it has at least this much time left.
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renewOnCallTime.SetValue(lease, TimeSpan.FromSeconds(2));
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}
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return lease;
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}
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#endif
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}
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}
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