diff options
Diffstat (limited to 'src/System.Private.CoreLib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs')
| -rw-r--r-- | src/System.Private.CoreLib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs | 117 |
1 files changed, 41 insertions, 76 deletions
diff --git a/src/System.Private.CoreLib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs b/src/System.Private.CoreLib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs index 562c195db..5d9b51bcc 100644 --- a/src/System.Private.CoreLib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs +++ b/src/System.Private.CoreLib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs @@ -7,7 +7,6 @@ using System.Collections.Generic; using System.Diagnostics; using System.Runtime.InteropServices; using System.Threading; - using Internal.Runtime.CompilerServices; namespace System.Runtime.CompilerServices @@ -17,6 +16,13 @@ namespace System.Runtime.CompilerServices where TKey : class where TValue : class { + #region Fields + private const int InitialCapacity = 8; // Initial length of the table. Must be a power of two. + private readonly Lock _lock; // This lock protects all mutation of data in the table. Readers do not take this lock. + private volatile Container _container; // The actual storage for the table; swapped out as the table grows. + private int _activeEnumeratorRefCount; // The number of outstanding enumerators on the table + #endregion + #region Constructors public ConditionalWeakTable() { @@ -165,8 +171,8 @@ namespace System.Runtime.CompilerServices // invokes createValueCallback() passing it the key. The returned value is bound to the key in the table // and returned as the result of GetValue(). // - // If multiple threads race to initialize the same key, the table may invoke createValueCallback - // multiple times with the same key. Exactly one of these calls will "win the race" and the returned + // If multiple threads try to initialize the same key, the table may invoke createValueCallback + // multiple times with the same key. Exactly one of these calls will succeed and the returned // value of that call will be the one added to the table and returned by all the racing GetValue() calls. // // This rule permits the table to invoke createValueCallback outside the internal table lock @@ -174,12 +180,7 @@ namespace System.Runtime.CompilerServices //-------------------------------------------------------------------------------------------- public TValue GetValue(TKey key, CreateValueCallback createValueCallback) { - // Our call to TryGetValue() validates key so no need for us to. - // - // if (key == null) - // { - // ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key); - // } + // key is validated by TryGetValue if (createValueCallback == null) { @@ -187,12 +188,9 @@ namespace System.Runtime.CompilerServices } TValue existingValue; - if (TryGetValue(key, out existingValue)) - { - return existingValue; - } - - return GetValueLocked(key, createValueCallback); + return TryGetValue(key, out existingValue) ? + existingValue : + GetValueLocked(key, createValueCallback); } private TValue GetValueLocked(TKey key, CreateValueCallback createValueCallback) @@ -226,10 +224,7 @@ namespace System.Runtime.CompilerServices // throw. //-------------------------------------------------------------------------------------------- - public TValue GetOrCreateValue(TKey key) - { - return GetValue(key, k => Activator.CreateInstance<TValue>()); - } + public TValue GetOrCreateValue(TKey key) => GetValue(key, _ => Activator.CreateInstance<TValue>()); public delegate TValue CreateValueCallback(TKey key); @@ -305,7 +300,7 @@ namespace System.Runtime.CompilerServices if (table != null) { // Ensure we don't keep the last current alive unnecessarily - _current = default(KeyValuePair<TKey, TValue>); + _current = default; // Decrement the ref count that was incremented when constructed using (LockHolder.Hold(table._lock)) @@ -399,10 +394,7 @@ namespace System.Runtime.CompilerServices c.CreateEntryNoResize(key, value); } - private static bool IsPowerOfTwo(int value) - { - return (value > 0) && ((value & (value - 1)) == 0); - } + private static bool IsPowerOfTwo(int value) => (value > 0) && ((value & (value - 1)) == 0); #endregion @@ -417,7 +409,7 @@ namespace System.Runtime.CompilerServices // // - Used with live key (linked into a bucket list where _buckets[hashCode & (_buckets.Length - 1)] points to first entry) // depHnd.IsAllocated == true, depHnd.GetPrimary() != null - // hashCode == RuntimeHelpers.GetHashCode(depHnd.GetPrimary()) & Int32.MaxValue + // hashCode == RuntimeHelpers.GetHashCode(depHnd.GetPrimary()) & int.MaxValue // next links to next Entry in bucket. // // - Used with dead key (linked into a bucket list where _buckets[hashCode & (_buckets.Length - 1)] points to first entry) @@ -453,10 +445,19 @@ namespace System.Runtime.CompilerServices // private sealed class Container { + private readonly ConditionalWeakTable<TKey, TValue> _parent; // the ConditionalWeakTable with which this container is associated + private int[] _buckets; // _buckets[hashcode & (_buckets.Length - 1)] contains index of the first entry in bucket (-1 if empty) + private Entry[] _entries; // the table entries containing the stored dependency handles + private int _firstFreeEntry; // _firstFreeEntry < _entries.Length => table has capacity, entries grow from the bottom of the table. + private bool _invalid; // flag detects if OOM or other background exception threw us out of the lock. + private bool _finalized; // set to true when initially finalized + private volatile object _oldKeepAlive; // used to ensure the next allocated container isn't finalized until this one is GC'd + internal Container(ConditionalWeakTable<TKey, TValue> parent) { Debug.Assert(parent != null); Debug.Assert(IsPowerOfTwo(InitialCapacity)); + int size = InitialCapacity; _buckets = new int[size]; for (int i = 0; i < _buckets.Length; i++) @@ -481,13 +482,7 @@ namespace System.Runtime.CompilerServices _firstFreeEntry = firstFreeEntry; } - internal bool HasCapacity - { - get - { - return _firstFreeEntry < _entries.Length; - } - } + internal bool HasCapacity => _firstFreeEntry < _entries.Length; internal int FirstFreeEntry => _firstFreeEntry; @@ -503,7 +498,7 @@ namespace System.Runtime.CompilerServices VerifyIntegrity(); _invalid = true; - int hashCode = RuntimeHelpers.GetHashCode(key) & Int32.MaxValue; + int hashCode = RuntimeHelpers.GetHashCode(key) & int.MaxValue; int newEntry = _firstFreeEntry++; _entries[newEntry].hashCode = hashCode; @@ -530,7 +525,7 @@ namespace System.Runtime.CompilerServices object secondary; int entryIndex = FindEntry(key, out secondary); value = Unsafe.As<TValue>(secondary); - return (entryIndex != -1); + return entryIndex != -1; } //---------------------------------------------------------------------------------------- @@ -542,17 +537,17 @@ namespace System.Runtime.CompilerServices //---------------------------------------------------------------------------------------- internal int FindEntry(TKey key, out object value) { - int hashCode = RuntimeHelpers.GetHashCode(key) & Int32.MaxValue; + int hashCode = RuntimeHelpers.GetHashCode(key) & int.MaxValue; int bucket = hashCode & (_buckets.Length - 1); for (int entriesIndex = Volatile.Read(ref _buckets[bucket]); entriesIndex != -1; entriesIndex = _entries[entriesIndex].next) { if (_entries[entriesIndex].hashCode == hashCode && _entries[entriesIndex].depHnd.GetPrimaryAndSecondary(out value) == key) { GC.KeepAlive(this); // ensure we don't get finalized while accessing DependentHandles. - return entriesIndex; } } + GC.KeepAlive(this); // ensure we don't get finalized while accessing DependentHandles. value = null; return -1; @@ -565,8 +560,8 @@ namespace System.Runtime.CompilerServices { if (index < _entries.Length) { - object oValue; - object oKey = _entries[index].depHnd.GetPrimaryAndSecondary(out oValue); + object oKey, oValue; + oKey = _entries[index].depHnd.GetPrimaryAndSecondary(out oValue); GC.KeepAlive(this); // ensure we don't get finalized while accessing DependentHandles. if (oKey != null) @@ -577,8 +572,8 @@ namespace System.Runtime.CompilerServices } } - key = default(TKey); - value = default(TValue); + key = default; + value = default; return false; } @@ -617,11 +612,9 @@ namespace System.Runtime.CompilerServices ref Entry entry = ref _entries[entryIndex]; - // // We do not free the handle here, as we may be racing with readers who already saw the hash code. // Instead, we simply overwrite the entry's hash code, so subsequent reads will ignore it. // The handle will be free'd in Container's finalizer, after the table is resized or discarded. - // Volatile.Write(ref entry.hashCode, -1); // Also, clear the key to allow GC to collect objects pointed to by the entry @@ -797,18 +790,10 @@ namespace System.Runtime.CompilerServices ~Container() { // We're just freeing per-appdomain unmanaged handles here. If we're already shutting down the AD, - // don't bother. - // - // (Despite its name, Environment.HasShutdownStart also returns true if the current AD is finalizing.) - - if (Environment.HasShutdownStarted) - { - return; - } - - //We also skip doing anything if the container is invalid, including if someone + // don't bother. (Despite its name, Environment.HasShutdownStart also returns true if the current + // AD is finalizing.) We also skip doing anything if the container is invalid, including if someone // the container object was allocated but its associated table never set. - if (_invalid || _parent == null) + if (Environment.HasShutdownStarted || _invalid || _parent == null) { return; } @@ -855,21 +840,7 @@ namespace System.Runtime.CompilerServices } } } - - private readonly ConditionalWeakTable<TKey, TValue> _parent; // the ConditionalWeakTable with which this container is associated - private int[] _buckets; // _buckets[hashcode & (_buckets.Length - 1)] contains index of the first entry in bucket (-1 if empty) - private Entry[] _entries; // the table entries containing the stored dependency handles - private int _firstFreeEntry; // _firstFreeEntry < _entries.Length => table has capacity, entries grow from the bottom of the table. - private bool _invalid; // flag detects if OOM or other background exception threw us out of the lock. - private bool _finalized; // set to true when initially finalized - private volatile object _oldKeepAlive; // used to ensure the next allocated container isn't finalized until this one is GC'd } - - private volatile Container _container; - private readonly Lock _lock; // This lock protects all mutation of data in the table. Readers do not take this lock. - private int _activeEnumeratorRefCount; // The number of outstanding enumerators on the table - - private const int InitialCapacity = 8; // Must be a power of two #endregion } #endregion @@ -902,25 +873,19 @@ namespace System.Runtime.CompilerServices internal struct DependentHandle { #region Constructors - public DependentHandle(Object primary, Object secondary) + public DependentHandle(object primary, object secondary) { _handle = RuntimeImports.RhHandleAllocDependent(primary, secondary); } #endregion #region Public Members - public bool IsAllocated - { - get - { - return _handle != (IntPtr)0; - } - } + public bool IsAllocated => _handle != IntPtr.Zero; // Getting the secondary object is more expensive than getting the first so // we provide a separate primary-only accessor for those times we only want the // primary. - public Object GetPrimary() + public object GetPrimary() { return RuntimeImports.RhHandleGet(_handle); } |