ircd::ctx::pool: Add option for dispatch strategy; behavior changed by default.

include/ircd/ctx/pool.h

@@ -115,6 +115,12 @@ struct ircd::ctx::pool::opts
 
 	/// Scheduler priority nice value for contexts in this pool.
 	int8_t nice {0};
+
+	/// Worker dispatch strategy.
+	/// - FIFO: Dispatch fairly (round-robin).
+	/// - LIFO: Dispatch the last to finish.
+	/// - SORT: Like LIFO but lower ID's are given partial precedence.
+	dock::opts dispatch {dock::opts::LIFO};
 };
 
 template<class F,

ircd/client.cc

@@ -90,6 +90,7 @@ ircd::client::pool_opts
 {
 	.stack_size = size_t(settings.stack_size),
 	.initial_ctxs = size_t(settings.pool_size),
+	.dispatch = ctx::dock::opts::SORT,
 };
 
 /// The pool of request contexts. When a client makes a request it does so by acquiring

ircd/ctx.cc

@@ -1589,9 +1589,14 @@ void
 ircd::ctx::pool::work()
 try
 {
+	const auto pop_opts
+	{
+		opt->dispatch
+	};
+
 	const auto func
 	{
-		q.pop()
+		q.pop(pop_opts)
 	};
 
 	const scope_notify notify