rename GetCommands() back to FinishProfiling() (akin to v1); add some obvious...

rename GetCommands() back to FinishProfiling() (akin to v1); add some obvious methods that avoid LINQ-to-Objects in a few cases, exploiting the fact that we can calculate the count as we reverse the list

StackExchange.Redis.Tests/Cluster.cs

@@ -596,7 +596,7 @@ public void SimpleProfiling()
                 var val = db.StringGet(key);
                 Assert.Equal("world", val);
 
-                var msgs = profiler.GetCommands();
+                var msgs = profiler.FinishProfiling();
                 Log("Checking GET...");
                 Assert.Contains(msgs, m => m.Command == "GET");
                 Log("Checking SET...");

StackExchange.Redis.Tests/Profiling.cs

@@ -35,7 +35,7 @@ public void Simple()
                 var s = (string)db.Execute("ECHO", "fii");
                 Assert.Equal("fii", s);
 
-                var cmds = session.GetCommands();
+                var cmds = session.FinishProfiling();
                 var i = 0;
                 foreach (var cmd in cmds)
                 {
@@ -121,7 +121,7 @@ public void ManyThreads()
                 threads.ForEach(thread => thread.Start());
                 threads.ForEach(thread => thread.Join());
 
-                var allVals = session.GetCommands();
+                var allVals = session.FinishProfiling();
                 var relevant = allVals.Where(cmd => cmd.Db > 0).ToList();
 
                 var kinds = relevant.Select(cmd => cmd.Command).Distinct().ToList();
@@ -178,7 +178,7 @@ public void ManyContexts()
 
                         Task.WaitAll(allTasks.ToArray());
 
-                        results[ix] = profiler.GetSession().GetCommands();
+                        results[ix] = profiler.GetSession().FinishProfiling();
                     });
 
                     threads.Add(thread);
@@ -252,7 +252,7 @@ public void LowAllocationEnumerable()
 
                 conn.WaitAll(allTasks.ToArray());
 
-                var res = session.GetCommands();
+                var res = session.FinishProfiling();
                 Assert.True(res.GetType().IsValueType);
 
                 using (var e = res.GetEnumerator())
@@ -312,7 +312,7 @@ public void ProfilingMD_Ex1()
                 threads.ForEach(thread => thread.Start());
                 threads.ForEach(thread => thread.Join());
 
-                IEnumerable<IProfiledCommand> timings = session.GetCommands();
+                IEnumerable<IProfiledCommand> timings = session.FinishProfiling();
 
                 Assert.Equal(16000, timings.Count());
             }
@@ -349,7 +349,7 @@ public void ProfilingMD_Ex2()
 
                         Task.WaitAll(threadTasks.ToArray());
 
-                        perThreadTimings[Thread.CurrentThread] = profiler.GetSession().GetCommands().ToList();
+                        perThreadTimings[Thread.CurrentThread] = profiler.GetSession().FinishProfiling().ToList();
                     });
 
                     threads.Add(thread);
@@ -388,7 +388,7 @@ public async Task ProfilingMD_Ex2_Async()
                             await db.StringSetAsync(prefix + j, "" + j);
                         }
 
-                        perThreadTimings.Add(profiler.GetSession().GetCommands().ToList());
+                        perThreadTimings.Add(profiler.GetSession().FinishProfiling().ToList());
                     });
 
                     tasks.Add(task);

StackExchange.Redis/StackExchange/Redis/Profiling/ProfiledCommandEnumerable.cs

-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
 
 namespace StackExchange.Redis.Profiling
 {
@@ -23,8 +26,7 @@ namespace StackExchange.Redis.Profiling
         /// </summary>
         public struct Enumerator : IEnumerator<IProfiledCommand>
         {
-            private ProfiledCommand Head;
-            private ProfiledCommand CurrentBacker;
+            private ProfiledCommand Head, CurrentBacker;
 
             private bool IsEmpty => Head == null;
             private bool IsUnstartedOrFinished => CurrentBacker == null;
@@ -65,26 +67,59 @@ public bool MoveNext()
             /// <summary>
             /// Resets the enumeration.
             /// </summary>
-            public void Reset()
-            {
-                CurrentBacker = null;
-            }
+            public void Reset() => CurrentBacker = null;
 
             /// <summary>
             /// Disposes the enumeration.
             /// subsequent attempts to enumerate results in undefined behavior.
             /// </summary>
-            public void Dispose()
+            public void Dispose() => CurrentBacker = Head = null;
+        }
+
+        private readonly ProfiledCommand _head;
+        private readonly int _count;
+        /// <summary>
+        /// Returns the number of commands captured in this snapshot
+        /// </summary>
+        public int Count() => _count;
+
+        /// <summary>
+        /// Returns the captured commands as an array
+        /// </summary>
+        public IProfiledCommand[] ToArray()
+        {   // exploit the fact that we know the length
+            if (_count == 0) return Array.Empty<IProfiledCommand>();
+
+            var arr = new IProfiledCommand[_count];
+            var cur = _head;
+            for(int i = 0; i < _count; i++)
             {
-                CurrentBacker = Head = null;
+                arr[i] = cur;
+                cur = cur.NextElement;
             }
+            return arr;
         }
 
-        private readonly ProfiledCommand Head;
-
-        internal ProfiledCommandEnumerable(ProfiledCommand head)
+        /// <summary>
+        /// Returns the captured commands as a list
+        /// </summary>
+        public List<IProfiledCommand> ToList()
+        {   // exploit the fact that we know the length
+            var list = new List<IProfiledCommand>(_count);
+            var cur = _head;
+            while (cur != null)
+            {
+                list.Add(cur);
+                cur = cur.NextElement;
+            }
+            return list;
+        }
+        internal ProfiledCommandEnumerable(int count, ProfiledCommand head)
         {
-            Head = head;
+            _count = count;
+            _head = head;
+
+            Debug.Assert(_count == Enumerable.Count(this));
         }
 
         /// <summary>
@@ -94,7 +129,7 @@ internal ProfiledCommandEnumerable(ProfiledCommand head)
         /// </para>
         /// <para>`foreach` will automatically use this method.</para>
         /// </summary>
-        public Enumerator GetEnumerator() => new Enumerator(Head);
+        public Enumerator GetEnumerator() => new Enumerator(_head);
 
         IEnumerator<IProfiledCommand> IEnumerable<IProfiledCommand>.GetEnumerator() => GetEnumerator();
 

StackExchange.Redis/StackExchange/Redis/Profiling/ProfilingSession.cs

@@ -33,13 +33,15 @@ internal void Add(ProfiledCommand command)
         }
 
         /// <summary>
-        /// Yield the commands that were captured as part of this session, resetting the session
+        /// Reset the session and yield the commands that were captured for enumeration; if additional commands
+        /// are added, they can be retrieved via additional calls to FinishProfiling
         /// </summary>
-        public ProfiledCommandEnumerable GetCommands()
+        public ProfiledCommandEnumerable FinishProfiling()
         {
             var head = (ProfiledCommand)Interlocked.Exchange(ref _untypedHead, null);
 
             // reverse the list so everything is ordered the way the consumer expected them
+            int count = 0;
             ProfiledCommand previous = null, current = head, next;
             while(current != null)
             {
@@ -47,9 +49,10 @@ public ProfiledCommandEnumerable GetCommands()
                 current.NextElement = previous;
                 previous = current;
                 current = next;
+                count++;
             }
 
-            return new ProfiledCommandEnumerable(previous);
+            return new ProfiledCommandEnumerable(count, previous);
         }
     }
 }