dohertj2/ScadaBridge
1
0
Fork 0
Code Issues 2 Pull Requests Actions Packages Projects Releases Wiki Activity

refactor(siteruntime): scope SiteScriptCompileCache to the ScriptCompilationService singleton — close register row 100

Browse Source 
The compile cache was a `static` class, so its entry table and its Hits/Count
counters were one process-global blob every test class in the SiteRuntime
assembly wrote into. Row 91 last wave neutered the resulting flakes (per-test
GUID keys + one-sided counter bounds), but the shared mutable state itself
remained: any test calling Clear() evicted entries other parallel classes had
just inserted, and a Clear() from a class outside the serialized collection
would degrade the others to recompiles and re-open the row-91 flake class.

PREMISE CORRECTION: the register speculated production clears "per-instance or
per-deployment script entries" and offered ClearKeys(prefix) as the natural fit.
There are NO production callers of Clear() at all — grep of src/ finds only
GetOrAdd (ScriptCompilationService.CompileCore). Clear() existed solely so
tests could reset the global. A key-scoped API would therefore have been new
production surface built for nobody, so the instance-scoped seam is the fix and
Clear() is deleted outright rather than migrated.

- SiteScriptCompileCache: `internal static class` -> `internal sealed class`;
  Cache/EvictionLock/_hits/_accessSequence become instance fields. LRU batch
  eviction, the double-checked sweep and the ConcurrentDictionary.ToArray()
  snapshot are byte-for-byte the same policy. Clear() removed.
- ScriptCompilationService owns one cache. Public ctor (the DI path) builds its
  own; a new internal ctor takes one for tests. Production N4 sharing is
  unchanged and now rests on the DI SINGLETON registration — the one service
  instance is threaded to DeployCompileValidator and to every Instance Actor —
  so that lifetime is load-bearing and is pinned by a new registration test.
- Tests: all three Clear() callers migrated off it. Each test now owns its cache,
  which lets the assertions get STRONGER — the row-91 workarounds are retired:
  Hits/Count are exact again (no >= baseline bounds), the per-test GUID key
  token is gone, and ForeignEntrySlack (512 entries of allowance on the bound)
  drops to the racing-thread count in the concurrency test. New test
  SeparateCaches_DoNotShareEntriesOrCounters pins the scoping directly: filling
  one cache past MaxEntries leaves another's entry, hit count and identity
  intact. DeploymentWarmThenGateTests additionally asserts Count == 1 now that
  its counter is private.
- The [Collection("SiteScriptCompileCache")] serialization from row 91 is
  RELAXED (removed from all three classes) — they no longer touch any shared
  state, so there is nothing left to serialize.
- Docs: Component-SiteRuntime.md gains the ownership/singleton note and drops
  the Clear() reference; DeploymentManagerActor / DeployCompileValidator /
  ServiceCollectionExtensions comments corrected to say where the cache lives.

Build: 0 warnings. SiteRuntime.Tests 643/643, three consecutive full-parallel
runs. AuditLog.Tests correlation classes (other ScriptCompilationService
consumers) green.
This commit is contained in:
Joseph Doherty
2026-08-17 06:03:58 -04:00
parent dcfcf822af
commit 84b405ff5f
10 changed files with 263 additions and 181 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tests/ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests/Scripts/SiteScriptCompileCacheTests.cs
+101 -107
View File
@@ -5,48 +5,34 @@ using ZB.MOM.WW.ScadaBridge.SiteRuntime.Scripts;
namespace ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests.Scripts;
/// <summary>
/// Tests for the process-wide <see cref="SiteScriptCompileCache"/>. The cache is
/// static/process-wide state, so this class shares the "SiteScriptCompileCache" xunit
/// collection with <c>ScriptCompilationServiceTests</c> and <c>DeploymentWarmThenGateTests</c>
/// (no cross-class parallelism between those three, so no concurrent
/// <see cref="SiteScriptCompileCache.Clear"/>).
/// Tests for <see cref="SiteScriptCompileCache"/>.
/// </summary>
/// <remarks>
/// <para>
/// <b>Deferred-work register row 91.</b> That collection does NOT stop the rest of the
/// assembly: any test class that compiles a script — Instance/Script actor tests, deployment
/// tests — goes through <see cref="SiteScriptCompileCache.GetOrAdd"/> too, in parallel, and
/// bumps the same process-global <see cref="SiteScriptCompileCache.Hits"/> /
/// <see cref="SiteScriptCompileCache.Count"/>. Absolute assertions such as
/// <c>Assert.Equal(1, Hits)</c> after a <c>Clear()</c> therefore only held while nothing else
/// happened to be compiling; they failed roughly 1 run in 4 of a full parallel solution run and
/// were always green in isolation.
/// <b>Deferred-work register row 100 — the cache is no longer static.</b> Every test here builds
/// its OWN <see cref="SiteScriptCompileCache"/>, so <see cref="SiteScriptCompileCache.Hits"/> and
/// <see cref="SiteScriptCompileCache.Count"/> count this test's compiles and nothing else. That
/// retires three workarounds this file used to carry:
/// </para>
/// <list type="bullet">
/// <item>the <c>[Collection("SiteScriptCompileCache")]</c> serialisation with
/// <c>ScriptCompilationServiceTests</c> and <c>DeploymentWarmThenGateTests</c> — those three
/// classes shared a mutable global and had to be kept off each other; they no longer touch any
/// shared state and run fully in parallel again;</item>
/// <item>the per-test GUID key token (register row 91) — no other class can reach this cache at
/// all, so keys need not be globally unique;</item>
/// <item>the one-sided counter bounds and the <c>ForeignEntrySlack = 512</c> allowance on
/// <c>Count</c> — foreign inserts are impossible now, so every assertion below is exact.</item>
/// </list>
/// <para>
/// The fix follows the register's row-74 pattern: assert the DELTA attributable to this test's
/// OWN keys across its own scoped action, never an absolute global value. Two habits carry it:
/// every test keys its cache entries on a per-test-instance unique token (<see cref="_uniq"/>),
/// so no other class can collide with or serve them; and the global counters are only ever
/// asserted as one-sided bounds (<c>&gt;= baseline + n</c>), since foreign traffic can only add.
/// A collection fixture spanning every script-compiling class in the assembly would fix it too,
/// but would serialise most of the suite for the benefit of five facts.
/// The old escape hatch, <c>Clear()</c>, is gone from the type: it had no production caller and
/// existed only to reset the global between tests. Constructing a cache is the reset.
/// </para>
/// </remarks>
[Collection("SiteScriptCompileCache")]
public class SiteScriptCompileCacheTests
{
/// <summary>
/// Slack allowed on <see cref="SiteScriptCompileCache.Count"/> bounds for entries inserted
/// by test classes outside this collection while a bound test runs (register row 91). The
/// exactness of the eviction claims comes from the per-key probes, not from this bound.
/// </summary>
private const int ForeignEntrySlack = 512;
/// <summary>Per-test-instance token making every cache key in this test uniquely ours.</summary>
private readonly string _uniq = Guid.NewGuid().ToString("N");
/// <summary>Builds a cache key body that no other test class in the assembly can produce.</summary>
private string Code(string body) => $"/*{_uniq}*/ {body}";
/// <summary>The cache under test. Private to this test instance — xunit builds one per test.</summary>
private readonly SiteScriptCompileCache _cache = new();
private static ScriptCompilationResult Ok() =>
ScriptCompilationResult.Succeeded(CSharpScript.Create<object?>("1", ScriptOptions.Default, typeof(ScriptGlobals)));
@@ -54,72 +40,94 @@ public class SiteScriptCompileCacheTests
[Fact]
public void GetOrAdd_SameCodeAndGlobals_ComputesOnce()
{
var code = Code("return 1;");
var hitsBefore = SiteScriptCompileCache.Hits;
var factoryCalls = 0;
ScriptCompilationResult Factory() { factoryCalls++; return Ok(); }
var r1 = SiteScriptCompileCache.GetOrAdd(code, typeof(ScriptGlobals), Factory);
var r2 = SiteScriptCompileCache.GetOrAdd(code, typeof(ScriptGlobals), Factory);
var r1 = _cache.GetOrAdd("return 1;", typeof(ScriptGlobals), Factory);
var r2 = _cache.GetOrAdd("return 1;", typeof(ScriptGlobals), Factory);
// Scoped to our own key, so these two are exact and are the real claim: one compile,
// and the second lookup returned that very instance rather than a re-computation.
Assert.Equal(1, factoryCalls);
Assert.Same(r1, r2);
// Hits is process-global; a parallel class's compile can only push the delta up, so the
// claim "the second lookup was counted as a hit" is a lower bound, not an equality.
Assert.True(SiteScriptCompileCache.Hits >= hitsBefore + 1,
$"expected the second GetOrAdd to register a hit; hits went {hitsBefore} -> {SiteScriptCompileCache.Hits}");
Assert.Equal(1, _cache.Hits);
Assert.Equal(1, _cache.Count);
}
[Fact]
public void GetOrAdd_SameCode_DifferentGlobals_AreSeparateEntries()
{
var code = Code("1 > 0");
var scriptCompiles = 0;
var triggerCompiles = 0;
var script = SiteScriptCompileCache.GetOrAdd(code, typeof(ScriptGlobals),
var script = _cache.GetOrAdd("1 > 0", typeof(ScriptGlobals),
() => { scriptCompiles++; return Ok(); });
var trigger = SiteScriptCompileCache.GetOrAdd(code, typeof(TriggerExpressionGlobals),
var trigger = _cache.GetOrAdd("1 > 0", typeof(TriggerExpressionGlobals),
() => { triggerCompiles++; return Ok(); });
// "No cross-globals hit" asserted where it is actually observable and ours: the second
// lookup had to compute, and the two globals surfaces hold distinct entries. (The old
// form — Count == 2 and Hits == 0 on the process-global counters — was only true while
// no other class was compiling.)
Assert.Equal(1, scriptCompiles);
Assert.Equal(1, triggerCompiles);
Assert.NotSame(script, trigger);
// Each entry is independently addressable afterwards: re-getting either must serve the
// matching cached result, never the other globals surface's.
Assert.Same(script, SiteScriptCompileCache.GetOrAdd(code, typeof(ScriptGlobals),
// Two distinct entries and no cross-globals hit — exact, because this cache is ours.
Assert.Equal(2, _cache.Count);
Assert.Equal(0, _cache.Hits);
// Each entry stays independently addressable afterwards.
Assert.Same(script, _cache.GetOrAdd("1 > 0", typeof(ScriptGlobals),
() => throw new InvalidOperationException("script entry was not cached")));
Assert.Same(trigger, SiteScriptCompileCache.GetOrAdd(code, typeof(TriggerExpressionGlobals),
Assert.Same(trigger, _cache.GetOrAdd("1 > 0", typeof(TriggerExpressionGlobals),
() => throw new InvalidOperationException("trigger entry was not cached")));
}
/// <summary>
/// Register row 100: two caches are genuinely independent stores. This is the property the
/// whole change exists for — one test class's cache activity can no longer evict, serve, or
/// be counted by another's. It is the direct replacement for the old
/// <c>Clear()</c>-under-a-serialized-collection arrangement.
/// </summary>
[Fact]
public void SeparateCaches_DoNotShareEntriesOrCounters()
{
var other = new SiteScriptCompileCache();
var mine = _cache.GetOrAdd("return 1;", typeof(ScriptGlobals), Ok);
_cache.GetOrAdd("return 1;", typeof(ScriptGlobals), Ok); // a hit on OUR cache
// The other cache has neither the entry nor the hit.
Assert.Equal(0, other.Count);
Assert.Equal(0, other.Hits);
// Same key, other store: it must compute its own value, and get a distinct instance.
var theirCompiles = 0;
var theirs = other.GetOrAdd("return 1;", typeof(ScriptGlobals),
() => { theirCompiles++; return Ok(); });
Assert.Equal(1, theirCompiles);
Assert.NotSame(mine, theirs);
// …and filling the other cache past its bound — the closest thing left to the old
// wholesale Clear() — leaves ours completely untouched.
for (var i = 0; i <= SiteScriptCompileCache.MaxEntries; i++)
other.GetOrAdd($"return {i};", typeof(ScriptGlobals), Ok);
Assert.Equal(1, _cache.Count);
Assert.Equal(1, _cache.Hits);
Assert.Same(mine, _cache.GetOrAdd("return 1;", typeof(ScriptGlobals),
() => throw new InvalidOperationException("our entry was evicted by another cache")));
}
[Fact]
public void Overflow_StaysWithinTheBound()
{
SiteScriptCompileCache.Clear();
for (var i = 0; i <= SiteScriptCompileCache.MaxEntries; i++)
SiteScriptCompileCache.GetOrAdd(Code($"return {i};"), typeof(ScriptGlobals), Ok);
_cache.GetOrAdd($"return {i};", typeof(ScriptGlobals), Ok);
// MaxEntries + 1 distinct inserts must not all be resident — the sweep ran. The bound
// carries slack for foreign inserts (register row 91); the sharp claim is the eviction
// probe below, which is scoped to keys only this test can produce.
Assert.True(SiteScriptCompileCache.Count <= SiteScriptCompileCache.MaxEntries + ForeignEntrySlack,
$"cache grew past its bound: {SiteScriptCompileCache.Count} vs max {SiteScriptCompileCache.MaxEntries}");
// MaxEntries + 1 distinct inserts, single-threaded: the sweep ran and the ceiling holds
// exactly (no foreign inserts can land here any more — register row 100).
Assert.True(_cache.Count <= SiteScriptCompileCache.MaxEntries,
$"cache grew past its bound: {_cache.Count} vs max {SiteScriptCompileCache.MaxEntries}");
var recomputed = 0;
for (var i = 0; i < 16; i++)
{
var code = Code($"return {i};");
SiteScriptCompileCache.GetOrAdd(code, typeof(ScriptGlobals), () => { recomputed++; return Ok(); });
}
_cache.GetOrAdd($"return {i};", typeof(ScriptGlobals), () => { recomputed++; return Ok(); });
Assert.True(recomputed > 0, "no oldest-batch entry was evicted — the overflow sweep did not run");
}
@@ -134,50 +142,37 @@ public class SiteScriptCompileCacheTests
[Fact]
public void Overflow_EvictsOldestBatch_AndKeepsRecentlyTouchedEntries()
{
// Note: the cache is process-wide static and other test classes compile into it
// concurrently, so the assertions below are phrased as properties of the eviction
// policy (what survives, what does not, nothing is wiped) rather than as exact
// counts, which no test can own here.
SiteScriptCompileCache.Clear();
// Fill to the bound. Entries 1..N are inserted oldest-first.
for (var i = 0; i < SiteScriptCompileCache.MaxEntries; i++)
SiteScriptCompileCache.GetOrAdd(Code($"return {i};"), typeof(ScriptGlobals), Ok);
_cache.GetOrAdd($"return {i};", typeof(ScriptGlobals), Ok);
// Touch entry 0 so it carries the NEWEST access stamp despite being inserted first.
var hot = SiteScriptCompileCache.GetOrAdd(Code("return 0;"), typeof(ScriptGlobals), Ok);
var hitsAfterTouch = SiteScriptCompileCache.Hits;
var hot = _cache.GetOrAdd("return 0;", typeof(ScriptGlobals), Ok);
var hitsAfterTouch = _cache.Hits;
Assert.Equal(1, hitsAfterTouch); // exactly one hit so far: the touch
// Push well past the bound so at least one eviction sweep definitely runs.
for (var i = 0; i < 200; i++)
SiteScriptCompileCache.GetOrAdd(Code($"return overflow{i};"), typeof(ScriptGlobals), Ok);
_cache.GetOrAdd($"return overflow{i};", typeof(ScriptGlobals), Ok);
// Nothing was cleared wholesale: the cache is still most of the way full and the hit
// counter survived (Clear() would have reset it to 0).
Assert.True(SiteScriptCompileCache.Count > SiteScriptCompileCache.MaxEntries / 2,
$"cache collapsed to {SiteScriptCompileCache.Count} entries — this looks like a wholesale clear");
Assert.True(SiteScriptCompileCache.Hits >= hitsAfterTouch);
// counter survived (a wholesale clear used to reset it to 0).
Assert.True(_cache.Count > SiteScriptCompileCache.MaxEntries / 2,
$"cache collapsed to {_cache.Count} entries — this looks like a wholesale clear");
Assert.Equal(hitsAfterTouch, _cache.Hits); // 200 distinct inserts, none of them hits
// The touched entry survived the sweep — a hit, not a recompile. This is the LRU
// property: recency, not insertion order, decides what stays.
var hitsBefore = SiteScriptCompileCache.Hits;
var again = SiteScriptCompileCache.GetOrAdd(Code("return 0;"), typeof(ScriptGlobals),
var again = _cache.GetOrAdd("return 0;", typeof(ScriptGlobals),
() => throw new InvalidOperationException("hot entry was evicted — LRU is not keeping recently-used entries"));
// Assert.Same is the sharp claim (our own key, our own instance). The counter check is a
// lower bound: Hits is process-global and a parallel class's hit lands in the same window
// (register row 91 — this was `Assert.Equal(hitsBefore + 1, …)`).
Assert.Same(hot, again);
Assert.True(SiteScriptCompileCache.Hits >= hitsBefore + 1,
$"expected the surviving hot entry to register a hit; hits went {hitsBefore} -> {SiteScriptCompileCache.Hits}");
Assert.Equal(hitsAfterTouch + 1, _cache.Hits);
// …and untouched old entries genuinely were evicted, so the sweep really ran.
var recomputed = 0;
for (var i = 1; i <= 16; i++)
{
var code = Code($"return {i};");
SiteScriptCompileCache.GetOrAdd(code, typeof(ScriptGlobals),
() => { recomputed++; return Ok(); });
}
_cache.GetOrAdd($"return {i};", typeof(ScriptGlobals), () => { recomputed++; return Ok(); });
Assert.True(recomputed > 0, "no old entry was evicted — the overflow sweep did not run");
}
@@ -189,26 +184,25 @@ public class SiteScriptCompileCacheTests
[Fact]
public async Task ConcurrentGetOrAddStorm_KeepsTheBound()
{
SiteScriptCompileCache.Clear();
const int perTask = 400;
var tasks = Enumerable.Range(0, 8).Select(t => Task.Run(() =>
const int tasks = 8;
await Task.WhenAll(Enumerable.Range(0, tasks).Select(t => Task.Run(() =>
{
for (var i = 0; i < perTask; i++)
SiteScriptCompileCache.GetOrAdd(Code($"return {t}_{i};"), typeof(ScriptGlobals), Ok);
}));
await Task.WhenAll(tasks);
_cache.GetOrAdd($"return {t}_{i};", typeof(ScriptGlobals), Ok);
})));
// A small transient overshoot is by design: threads that lose the double-checked
// eviction race still insert their own entry afterwards, so the ceiling is "bounded",
// not "never exceeded by one". The property under test is that 3200 distinct inserts
// do not accumulate — before WP3.1 this was a wholesale Clear(), and a per-entry
// eviction bug would show up here as unbounded growth, not as a handful of extra rows.
// (Other test classes compile into this process-wide cache concurrently, which is the
// other reason the bound is asserted with slack rather than exactly.)
Assert.True(SiteScriptCompileCache.Count <= SiteScriptCompileCache.MaxEntries + ForeignEntrySlack,
$"cache grew past its bound: {SiteScriptCompileCache.Count} vs max {SiteScriptCompileCache.MaxEntries} " +
$"after {8 * perTask} distinct inserts");
// not "never exceeded by one". The slack is bounded by the number of racing threads
// (register row 100 — it used to be 512, to absorb inserts from other test classes
// sharing the process-global cache; nothing foreign can reach this instance).
// The property under test is that 3200 distinct inserts do not accumulate — before
// WP3.1 this was a wholesale clear, and a per-entry eviction bug would show up here as
// unbounded growth, not as a handful of extra rows.
Assert.True(_cache.Count <= SiteScriptCompileCache.MaxEntries + tasks,
$"cache grew past its bound: {_cache.Count} vs max {SiteScriptCompileCache.MaxEntries} " +
$"(+{tasks} racing-insert slack) after {tasks * perTask} distinct inserts");
}
}