ircd::ctx: Split this_ctx devices into files; minor interface tweaks.

include/ircd/ctx/critical_assertion.h

@@ -0,0 +1,37 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_CTX_CRITICAL_ASSERTION_H
+
+namespace ircd::ctx::this_ctx
+{
+	struct critical_assertion;                   // Assert no yielding for a section
+}
+
+/// An instance of critical_assertion detects an attempt to context switch.
+///
+/// For when the developer specifically does not want any yielding in a
+/// section or anywhere up the stack from it. This device does not prevent
+/// a switch and may carry no meaning outside of debug-mode compilation. It is
+/// good practice to use this device even when it appears obvious the
+/// section's callgraph has no chance of yielding: code changes, and everything
+/// up the graph can change without taking notice of your section.
+///
+class ircd::ctx::this_ctx::critical_assertion
+{
+	#ifndef NDEBUG
+	bool theirs;
+
+  public:
+	critical_assertion();
+	~critical_assertion() noexcept;
+	#endif
+};

include/ircd/ctx/critical_indicator.h

@@ -0,0 +1,38 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_CTX_CRITICAL_INDICATOR_H
+
+namespace ircd::ctx::this_ctx
+{
+	struct critical_indicator;                   // Indicates if yielding happened for a section
+}
+
+/// An instance of critical_indicator reports if context switching happened.
+///
+/// A critical_indicator remains true after construction until a context switch
+/// has occurred. It then becomes false. This is not an assertion and is
+/// available in optimized builds for real use. For example, a context may
+/// want to recompute some value after a context switch and opportunistically
+/// skip this effort when this indicator shows no switch occurred.
+///
+class ircd::ctx::this_ctx::critical_indicator
+{
+	uint64_t state;
+
+  public:
+	uint64_t count() const             { return yields(cur()) - state;         }
+	operator bool() const              { return yields(cur()) == state;        }
+
+	critical_indicator()
+	:state{yields(cur())}
+	{}
+};

include/ircd/ctx/ctx.h

@@ -55,9 +55,9 @@ namespace ircd::ctx
 	const int64_t &notes(const ctx &);           // Peeks at internal semaphore count
 	const uint64_t &yields(const ctx &);         // Context switching counter
 	const ulong &cycles(const ctx &);            // Accumulated tsc (not counting cur slice)
-	bool interruptible(const ctx &);             // Context can throw at interruption point
-	bool interruption(const ctx &);              // Context was marked for interruption
-	bool termination(const ctx &);               // Context was marked for termination
+	bool interruptible(const ctx &) noexcept;    // Context can throw at interruption point
+	bool interruption(const ctx &) noexcept;     // Context was marked for interruption
+	bool termination(const ctx &) noexcept;      // Context was marked for termination
 	bool finished(const ctx &);                  // Context function returned (or exception).
 	bool started(const ctx &);                   // Context was ever entered.
 	bool running(const ctx &);                   // Context is the currently running ctx.
@@ -73,6 +73,11 @@ namespace ircd::ctx
 }
 
 #include "this_ctx.h"
+#include "stack_usage_assertion.h"
+#include "critical_assertion.h"
+#include "critical_indicator.h"
+#include "exception_handler.h"
+#include "uninterruptible.h"
 #include "prof.h"
 #include "list.h"
 #include "dock.h"

include/ircd/ctx/exception_handler.h

@@ -0,0 +1,38 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_CTX_EXCEPTION_HANDLER_H
+
+namespace ircd::ctx::this_ctx
+{
+	struct exception_handler;
+}
+
+/// An instance of exception_handler must be present to allow a context
+/// switch inside a catch block. This is due to ABI limitations that stack
+/// exceptions with thread-local assumptions and don't expect catch blocks
+/// on the same thread to interleave when we switch the stack.
+///
+/// We first increment the refcount for the caught exception so it remains
+/// intuitively accessible for the rest of the catch block. Then the presence
+/// of this object makes the ABI believe the catch block has ended.
+///
+/// The exception cannot then be rethrown. DO NOT RETHROW THE EXCEPTION.
+///
+struct ircd::ctx::this_ctx::exception_handler
+:std::exception_ptr
+{
+	exception_handler() noexcept;
+	exception_handler(exception_handler &&) = delete;
+	exception_handler(const exception_handler &) = delete;
+	exception_handler &operator=(exception_handler &&) = delete;
+	exception_handler &operator=(const exception_handler &) = delete;
+};

include/ircd/ctx/prof.h

@@ -39,6 +39,9 @@ namespace ircd::ctx::prof
 	void mark(const event &);
 }
 
+/// Profiling events for marking. These are currently used internally at the
+/// appropriate point to mark(): the user of ircd::ctx has no reason to mark()
+/// these events; this interface is not quite developed for general use yet.
 enum class ircd::ctx::prof::event
 {
 	SPAWN,             // Context spawn requested

include/ircd/ctx/stack_usage_assertion.h

@@ -0,0 +1,35 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_CTX_STACK_USAGE_ASSERTION_H
+
+namespace ircd::ctx::this_ctx
+{
+	struct stack_usage_assertion;
+
+	size_t stack_at_here() __attribute__((noinline));
+}
+
+/// An instance of stack_usage_assertion is placed on a ctx stack where one
+/// wants to test the stack usage at both construction and destruction points
+/// to ensure it is less than the value set in ctx::prof::settings which is
+/// generally some engineering safety factor of 2-3 etc. This should not be
+/// entirely relied upon except during debug builds, however we may try to
+/// provide an optimized build mode enabling these to account for any possible
+/// differences in the stack between the environments.
+///
+struct ircd::ctx::this_ctx::stack_usage_assertion
+{
+	#ifndef NDEBUG
+	stack_usage_assertion();
+	~stack_usage_assertion() noexcept;
+	#endif
+};

include/ircd/ctx/this_ctx.h

@@ -15,28 +15,18 @@ namespace ircd::ctx {
 /// Interface to the currently running context
 inline namespace this_ctx
 {
-	struct critical_indicator;                   // Indicates if yielding happened for a section
-	struct critical_assertion;                   // Assert no yielding for a section
-	struct exception_handler;                    // Must be present to yield in a handler
-	struct uninterruptible;                      // Scope convenience for interruptible()
-
 	struct ctx &cur();                           ///< Assumptional reference to *current
-
 	const uint64_t &id();                        // Unique ID for cur ctx
 	string_view name();                          // Optional label for cur ctx
 
+	ulong cycles_here();                         // misc profiling related
+
+	bool interruption_requested();               // interruption(cur())
+	void interruption_point();                   // throws if interruption_requested()
+
 	void wait();                                 // Returns when context is woken up.
 	void yield();                                // Allow other contexts to run before returning.
 
-	void interruption_point();                   // throws if interruption_requested()
-	bool interruption_requested();               // interruption(cur())
-	void interruptible(const bool &);            // interruptible(cur(), bool) +INTERRUPTION POINT
-	void interruptible(const bool &, std::nothrow_t) noexcept;
-
-	struct stack_usage_assertion;                // Assert safety factor (see ctx/prof.h)
-	size_t stack_at_here() __attribute__((noinline));
-	ulong cycles_here();
-
 	// Return remaining time if notified; or <= 0 if not, and timeout thrown on throw overloads
 	microseconds wait(const microseconds &, const std::nothrow_t &);
 	template<class E, class duration> nothrow_overload<E, duration> wait(const duration &);
@@ -59,116 +49,6 @@ namespace ircd::ctx
 	extern __thread ctx *current;
 }
 
-/// An instance of stack_usage_assertion is placed on a ctx stack where one
-/// wants to test the stack usage at both construction and destruction points
-/// to ensure it is less than the value set in ctx::prof::settings which is
-/// generally some engineering safety factor of 2-3 etc. This should not be
-/// entirely relied upon except during debug builds, however we may try to
-/// provide an optimized build mode enabling these to account for any possible
-/// differences in the stack between the environments.
-///
-struct ircd::ctx::this_ctx::stack_usage_assertion
-{
-	#ifndef NDEBUG
-	stack_usage_assertion();
-	~stack_usage_assertion() noexcept;
-	#endif
-};
-
-/// An instance of critical_assertion detects an attempt to context switch.
-///
-/// For when the developer specifically does not want any yielding in a
-/// section or anywhere up the stack from it. This device does not prevent
-/// a switch and may carry no meaning outside of debug-mode compilation. It is
-/// good practice to use this device even when it appears obvious the
-/// section's callgraph has no chance of yielding: code changes, and everything
-/// up the graph can change without taking notice of your section.
-///
-class ircd::ctx::this_ctx::critical_assertion
-{
-	#ifndef NDEBUG
-	bool theirs;
-
-  public:
-	critical_assertion();
-	~critical_assertion() noexcept;
-	#endif
-};
-
-/// An instance of critical_indicator reports if context switching happened.
-///
-/// A critical_indicator remains true after construction until a context switch
-/// has occurred. It then becomes false. This is not an assertion and is
-/// available in optimized builds for real use. For example, a context may
-/// want to recompute some value after a context switch and opportunistically
-/// skip this effort when this indicator shows no switch occurred.
-///
-class ircd::ctx::this_ctx::critical_indicator
-{
-	uint64_t state;
-
-  public:
-	uint64_t count() const             { return yields(cur()) - state;         }
-	operator bool() const              { return yields(cur()) == state;        }
-
-	critical_indicator()
-	:state{yields(cur())}
-	{}
-};
-
-/// An instance of exception_handler must be present to allow a context
-/// switch inside a catch block. This is due to ABI limitations that stack
-/// exceptions with thread-local assumptions and don't expect catch blocks
-/// on the same thread to interleave when we switch the stack.
-///
-/// We first increment the refcount for the caught exception so it remains
-/// intuitively accessible for the rest of the catch block. Then the presence
-/// of this object makes the ABI believe the catch block has ended.
-///
-/// The exception cannot then be rethrown. DO NOT RETHROW THE EXCEPTION.
-///
-struct ircd::ctx::this_ctx::exception_handler
-:std::exception_ptr
-{
-	exception_handler() noexcept;
-	exception_handler(exception_handler &&) = delete;
-	exception_handler(const exception_handler &) = delete;
-	exception_handler &operator=(exception_handler &&) = delete;
-	exception_handler &operator=(const exception_handler &) = delete;
-};
-
-/// An instance of uninterruptible will suppress interrupts sent to the
-/// context for the scope. Suppression does not discard any interrupt,
-/// it merely ignores it at all interruption points until the suppression
-/// ends, after which it will be thrown.
-///
-struct ircd::ctx::this_ctx::uninterruptible
-{
-	struct nothrow;
-
-	bool theirs;
-
-	uninterruptible();
-	uninterruptible(uninterruptible &&) = delete;
-	uninterruptible(const uninterruptible &) = delete;
-	~uninterruptible() noexcept(false);
-};
-
-/// A variant of uinterruptible for users that must guarantee the ending of
-/// the suppression scope will not be an interruption point. The default
-/// behavior for uninterruptible is to throw, even from its destructor, to
-/// fulfill the interruption request without any more delay.
-///
-struct ircd::ctx::this_ctx::uninterruptible::nothrow
-{
-	bool theirs;
-
-	nothrow() noexcept;
-	nothrow(nothrow &&) = delete;
-	nothrow(const nothrow &) = delete;
-	~nothrow() noexcept;
-};
-
 /// This overload matches ::sleep() and acts as a drop-in for ircd contexts.
 /// interruption point.
 inline void

include/ircd/ctx/uninterruptible.h

@@ -0,0 +1,53 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_CTX_UNINTERRUPTIBLE_H
+
+namespace ircd::ctx::this_ctx
+{
+	struct uninterruptible;
+
+	bool interruptible() noexcept;
+	void interruptible(const bool &);
+	void interruptible(const bool &, std::nothrow_t) noexcept;
+}
+
+/// An instance of uninterruptible will suppress interrupts sent to the
+/// context for the scope. Suppression does not discard any interrupt,
+/// it merely ignores it at all interruption points until the suppression
+/// ends, after which it will be thrown.
+///
+struct ircd::ctx::this_ctx::uninterruptible
+{
+	struct nothrow;
+
+	bool theirs;
+
+	uninterruptible();
+	uninterruptible(uninterruptible &&) = delete;
+	uninterruptible(const uninterruptible &) = delete;
+	~uninterruptible() noexcept(false);
+};
+
+/// A variant of uinterruptible for users that must guarantee the ending of
+/// the suppression scope will not be an interruption point. The default
+/// behavior for uninterruptible is to throw, even from its destructor, to
+/// fulfill the interruption request without any more delay.
+///
+struct ircd::ctx::this_ctx::uninterruptible::nothrow
+{
+	bool theirs;
+
+	nothrow() noexcept;
+	nothrow(nothrow &&) = delete;
+	nothrow(const nothrow &) = delete;
+	~nothrow() noexcept;
+};

ircd/ctx.cc

@@ -423,6 +423,7 @@ ircd::ctx::finished(const ctx &ctx)
 /// Indicates if `ctx` was terminated; does not clear the flag
 bool
 ircd::ctx::termination(const ctx &c)
+noexcept
 {
 	return c.flags & context::TERMINATED;
 }
@@ -430,6 +431,7 @@ ircd::ctx::termination(const ctx &c)
 /// Indicates if `ctx` was interrupted; does not clear the flag
 bool
 ircd::ctx::interruption(const ctx &c)
+noexcept
 {
 	return c.flags & context::INTERRUPTED;
 }
@@ -437,6 +439,7 @@ ircd::ctx::interruption(const ctx &c)
 /// Indicates if `ctx` will suppress any interrupts.
 bool
 ircd::ctx::interruptible(const ctx &c)
+noexcept
 {
 	return c.flags & ~context::NOINTERRUPT;
 }
@@ -607,8 +610,6 @@ ircd::ctx::this_ctx::interruptible(const bool &b)
 		interruption_point();
 }
 
-/// Throws interrupted if the currently running context was interrupted
-/// and clears the interrupt flag.
 void
 ircd::ctx::this_ctx::interruptible(const bool &b,
                                    std::nothrow_t)
@@ -617,6 +618,13 @@ noexcept
 	interruptible(cur(), b);
 }
 
+bool
+ircd::ctx::this_ctx::interruptible()
+noexcept
+{
+	return interruptible(cur());
+}
+
 /// Throws interrupted if the currently running context was interrupted
 /// and clears the interrupt flag.
 void