1 files changed, 67 insertions, 3 deletions

diff --git a/src/csharp/Grpc.Core/Metadata.cs b/src/csharp/Grpc.Core/Metadata.cs
index 915bec146c..6fc715d6ee 100644
--- a/src/csharp/Grpc.Core/Metadata.cs
+++ b/src/csharp/Grpc.Core/Metadata.cs
@@ -95,11 +95,18 @@ namespace Grpc.Core
 
         #region IList members
 
+
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public int IndexOf(Metadata.Entry item)
         {
             return entries.IndexOf(item);
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public void Insert(int index, Metadata.Entry item)
         {
             GrpcPreconditions.CheckNotNull(item);
@@ -107,12 +114,18 @@ namespace Grpc.Core
             entries.Insert(index, item);
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public void RemoveAt(int index)
         {
             CheckWriteable();
             entries.RemoveAt(index);
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public Metadata.Entry this[int index]
         {
             get
@@ -128,6 +141,9 @@ namespace Grpc.Core
             }
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public void Add(Metadata.Entry item)
         {
             GrpcPreconditions.CheckNotNull(item);
@@ -135,48 +151,75 @@ namespace Grpc.Core
             entries.Add(item);
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public void Add(string key, string value)
         {
             Add(new Entry(key, value));
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public void Add(string key, byte[] valueBytes)
         {
             Add(new Entry(key, valueBytes));
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public void Clear()
         {
             CheckWriteable();
             entries.Clear();
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public bool Contains(Metadata.Entry item)
         {
             return entries.Contains(item);
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public void CopyTo(Metadata.Entry[] array, int arrayIndex)
         {
             entries.CopyTo(array, arrayIndex);
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public int Count
         {
             get { return entries.Count; }
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public bool IsReadOnly
         {
             get { return readOnly; }
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public bool Remove(Metadata.Entry item)
         {
             CheckWriteable();
             return entries.Remove(item);
         }
 
+        /// <summary>
+        /// <see cref="T:IList`1"/>
+        /// </summary>
         public IEnumerator<Metadata.Entry> GetEnumerator()
         {
             return entries.GetEnumerator();
@@ -221,7 +264,7 @@ namespace Grpc.Core
             public Entry(string key, byte[] valueBytes)
             {
                 this.key = NormalizeKey(key);
-                GrpcPreconditions.CheckArgument(this.key.EndsWith(BinaryHeaderSuffix),
+                GrpcPreconditions.CheckArgument(HasBinaryHeaderSuffix(this.key),
                     "Key for binary valued metadata entry needs to have suffix indicating binary value.");
                 this.value = null;
                 GrpcPreconditions.CheckNotNull(valueBytes, "valueBytes");
@@ -237,7 +280,7 @@ namespace Grpc.Core
             public Entry(string key, string value)
             {
                 this.key = NormalizeKey(key);
-                GrpcPreconditions.CheckArgument(!this.key.EndsWith(BinaryHeaderSuffix),
+                GrpcPreconditions.CheckArgument(!HasBinaryHeaderSuffix(this.key),
                     "Key for ASCII valued metadata entry cannot have suffix indicating binary value.");
                 this.value = GrpcPreconditions.CheckNotNull(value, "value");
                 this.valueBytes = null;
@@ -324,7 +367,7 @@ namespace Grpc.Core
             /// </summary>
             internal static Entry CreateUnsafe(string key, byte[] valueBytes)
             {
-                if (key.EndsWith(BinaryHeaderSuffix))
+                if (HasBinaryHeaderSuffix(key))
                 {
                     return new Entry(key, null, valueBytes);
                 }
@@ -338,6 +381,27 @@ namespace Grpc.Core
                     "Metadata entry key not valid. Keys can only contain lowercase alphanumeric characters, underscores and hyphens.");
                 return normalized;
             }
+
+            /// <summary>
+            /// Returns <c>true</c> if the key has "-bin" binary header suffix.
+            /// </summary>
+            private static bool HasBinaryHeaderSuffix(string key)
+            {
+                // We don't use just string.EndsWith because its implementation is extremely slow
+                // on CoreCLR and we've seen significant differences in gRPC benchmarks caused by it.
+                // See https://github.com/dotnet/coreclr/issues/5612
+
+                int len = key.Length;
+                if (len >= 4 &&
+                    key[len - 4] == '-' &&
+                    key[len - 3] == 'b' &&
+                    key[len - 2] == 'i' &&
+                    key[len - 1] == 'n')
+                {
+                    return true;
+                }
+                return false;
+            }
         }
     }
 }