CompilationPipeline.compilationStarted

Parameters

Description

An event that is invoked on the main thread when the compilation of assemblies starts.

CompilationPipeline.compilationStarted is called before the first CompilationPipeline.assemblyCompilationStarted event.

You can use the context to match CompilationPipeline.compilationStarted and CompilationPipeline.compilationFinished events that belong to the same compilation cycle. Compilation start and finish events from the same compilation cycle have the same context instance. Treat the context only as an identifier: compare by reference or use it as a dictionary key, but don't assume any structure or string representation.

If multiple compilations happen concurrently or in quick succession, you can use the context to associate timing, logging, error counts, or any per-compilation data with the right compilation cycle. For example, on compilation start, you can create an entry referenced by the context as a key, and capture start time or relevant state. On compilation finish, you can then look up the same entry via the context, compute duration, summarize results, and clean up.

using System;
using System.Collections.Generic;
using UnityEditor;
using UnityEditor.Compilation;

[InitializeOnLoad]
public static class CompilationTracker
{
    // Store per-compilation data keyed by the context object
    private static readonly Dictionary<object, CompilationInfo> _compilations = new();

    static CompilationTracker()
    {
        CompilationPipeline.compilationStarted += OnCompilationStarted;
        CompilationPipeline.compilationFinished += OnCompilationFinished;
    }

    private static void OnCompilationStarted(object context)
    {
        _compilations[context] = new CompilationInfo
        {
            StartTime = DateTime.UtcNow,
            TriggerSummary = "Scripts changed or domain reload pending" // whatever you want to record
        };

        // Optional: log or prepare resources
        UnityEngine.Debug.Log("Compilation started");
    }

    private static void OnCompilationFinished(object context)
    {
        if (_compilations.TryGetValue(context, out var info))
        {
            var duration = DateTime.UtcNow - info.StartTime;

            // You can also inspect CompilationPipeline.GetAssemblies() or other APIs here
            UnityEngine.Debug.Log($"Compilation finished in {duration.TotalSeconds:F2}s");

            // Clean up
            _compilations.Remove(context);
        }
        else
        {
            // In case something slipped through, avoid leaking state
            UnityEngine.Debug.LogWarning("Compilation finished, but no matching context found.");
        }
    }

    private class CompilationInfo
    {
        public DateTime StartTime;
        public string TriggerSummary;
    }
}