//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// kernel -- Header containing the core of the kernel API
//
// Author           : Thierry Delisle
// Created On       : Tue Jan 17 12:27:26 2017
// Last Modified By : Peter A. Buhr
// Last Modified On : Tue Feb  4 12:29:26 2020
// Update Count     : 22
//

#pragma once

#include "invoke.h"
#include "time_t.hfa"
#include "coroutine.hfa"

#include "containers/list.hfa"

extern "C" {
	#include <bits/pthreadtypes.h>
	#include <pthread.h>
	#include <linux/types.h>
}

#ifdef __CFA_WITH_VERIFY__
	extern bool __cfaabi_dbg_in_kernel();
#endif

//-----------------------------------------------------------------------------
// I/O
struct cluster;
struct io_context$;
struct io_arbiter$;

struct io_context_params {
	int num_entries;
};

void  ?{}(io_context_params & this);

//-----------------------------------------------------------------------------
// Processor
extern struct cluster * mainCluster;

// Coroutine used py processors for the 2-step context switch

struct processorCtx_t {
	struct coroutine$ self;
	struct processor * proc;
};

struct io_future_t;

// Information needed for idle sleep
struct __fd_waitctx {
	// semaphore/future like object
	// values can be 0, 1 or some file descriptor.
	// 0 - is the default state
	// 1 - means the proc should wake-up immediately
	// FD - means the proc is going asleep and should be woken by writing to the FD.
	volatile int sem;

	// The event FD that corresponds to this processor
	int evfd;

	// buffer into which the proc will read from evfd
	// unused if not using io_uring for idle sleep
	void * rdbuf;

	// future use to track the read of the eventfd
	// unused if not using io_uring for idle sleep
	io_future_t * ftr;

	volatile unsigned long long wake__time;
	volatile unsigned long long sleep_time;
	volatile unsigned long long drain_time;
};

// Wrapper around kernel threads
struct __attribute__((aligned(64))) processor {
	// Cluster from which to get threads
	struct cluster * cltr;

	// Ready Queue state per processor
	struct {
		unsigned short its;
		unsigned short itr;
		unsigned id;
		unsigned target;
		unsigned last;
		signed   cpu;
	} rdq;

	// Set to true to notify the processor should terminate
	volatile bool do_terminate;

	// Coroutine ctx who does keeps the state of the processor
	struct processorCtx_t runner;

	// Name of the processor
	const char * name;

	// Handle to pthreads
	pthread_t kernel_thread;

	// Unique id for the processor (not per cluster)
	unsigned unique_id;

	struct {
		io_context$ * ctx;
		unsigned target;
		volatile bool pending;
		volatile bool dirty;
	} io;

	// Preemption data
	// Node which is added in the discrete event simulaiton
	struct alarm_node_t * preemption_alarm;

	// If true, a preemption was triggered in an unsafe region, the processor must preempt as soon as possible
	bool pending_preemption;

	// context for idle sleep
	struct __fd_waitctx idle_wctx;

	// Termination synchronisation (user semaphore)
	oneshot terminated;

	// pthread Stack
	void * stack;

	// Link lists fields
	dlink(processor) link;

	// special init fields
	// This is needed for memcached integration
	// once memcached experiments are done this should probably be removed
	// it is not a particularly safe scheme as it can make processors less homogeneous
	struct {
		thread$ * thrd;
	} init;

	struct KernelThreadData * local_data;

	#if !defined(__CFA_NO_STATISTICS__)
		int print_stats;
		bool print_halts;
	#endif

#ifdef __CFA_DEBUG__
	// Last function to enable preemption on this processor
	const char * last_enable;
#endif
};
// P9_EMBEDDED( processor, dlink(processor) )
static inline tytagref( dlink(processor), dlink(processor) ) ?`inner( processor & this ) {
    dlink(processor) & b = this.link;
    tytagref( dlink(processor), dlink(processor) ) result = { b };
    return result;
}

void  ?{}(processor & this, const char name[], struct cluster & cltr);
void ^?{}(processor & this);

static inline void  ?{}(processor & this)                        { this{ "Anonymous Processor", *mainCluster}; }
static inline void  ?{}(processor & this, struct cluster & cltr) { this{ "Anonymous Processor", cltr}; }
static inline void  ?{}(processor & this, const char name[])     { this{name, *mainCluster}; }

//-----------------------------------------------------------------------------
// Cluster Tools

// Intrusives lanes which are used by the ready queue
union __attribute__((aligned(64))) __intrusive_lane_t;
void  ?{}(__intrusive_lane_t & this);
void ^?{}(__intrusive_lane_t & this);

// Aligned timestamps which are used by the ready queue and io subsystem
union __attribute__((aligned(64))) __timestamp_t {
	struct {
		volatile unsigned long long tv;
		volatile unsigned long long ma;
	} t;
	char __padding[192];
};

static inline void  ?{}(__timestamp_t & this) { this.t.tv = 0; this.t.ma = 0; }
static inline void ^?{}(__timestamp_t &) {}


struct __attribute__((aligned(16))) __cache_id_t {
	volatile unsigned id;
};

// Idle Sleep
struct __cluster_proc_list {
	// Spin lock protecting the queue
	__spinlock_t lock;

	// FD to use to wake a processor
	struct __fd_waitctx * volatile fdw;

	// Total number of processors
	unsigned total;

	// Total number of idle processors
	unsigned idle;

	// List of idle processors
	dlist(processor) idles;

	// List of active processors
	dlist(processor) actives;
};

//-----------------------------------------------------------------------------
// Cluster
struct __attribute__((aligned(64))) cluster {
	struct {
		struct {
			// Arary of subqueues
			__intrusive_lane_t * data;

			// Time since subqueues were processed
			__timestamp_t * tscs;

			// Number of subqueue / timestamps
			size_t count;
		} readyQ;

		struct {
			// Array of $io_
			io_context$ ** data;

 			// Time since subqueues were processed
			__timestamp_t * tscs;

			// Number of I/O subqueues
 			size_t count;
		} io;

		// Cache each kernel thread belongs to
		__cache_id_t * caches;
	} sched;

	// // Ready queue for threads
	// __ready_queue_t ready_queue;

	// Name of the cluster
	const char * name;

	// Preemption rate on this cluster
	Duration preemption_rate;

	// List of idle processors
	__cluster_proc_list procs;

	// List of threads
	__spinlock_t thread_list_lock;
	__dllist_t(struct thread$) threads;
	unsigned int nthreads;

	// Link lists fields
	struct __dbg_node_cltr {
		cluster * next;
		cluster * prev;
	} node;

	struct {
		io_arbiter$ * arbiter;
		io_context_params params;
	} io;

	#if !defined(__CFA_NO_STATISTICS__)
		struct __stats_t * stats;
		int print_stats;
	#endif
};
extern Duration default_preemption();

void ?{} (cluster & this, const char name[], Duration preemption_rate, unsigned num_io, const io_context_params & io_params);
void ^?{}(cluster & this);

static inline void ?{} (cluster & this)                                            { io_context_params default_params;    this{"Anonymous Cluster", default_preemption(), 1, default_params}; }
static inline void ?{} (cluster & this, Duration preemption_rate)                  { io_context_params default_params;    this{"Anonymous Cluster", preemption_rate, 1, default_params}; }
static inline void ?{} (cluster & this, const char name[])                         { io_context_params default_params;    this{name, default_preemption(), 1, default_params}; }
static inline void ?{} (cluster & this, unsigned num_io)                           { io_context_params default_params;    this{"Anonymous Cluster", default_preemption(), num_io, default_params}; }
static inline void ?{} (cluster & this, Duration preemption_rate, unsigned num_io) { io_context_params default_params;    this{"Anonymous Cluster", preemption_rate, num_io, default_params}; }
static inline void ?{} (cluster & this, const char name[], unsigned num_io)        { io_context_params default_params;    this{name, default_preemption(), num_io, default_params}; }
static inline void ?{} (cluster & this, const io_context_params & io_params)                                            { this{"Anonymous Cluster", default_preemption(), 1, io_params}; }
static inline void ?{} (cluster & this, Duration preemption_rate, const io_context_params & io_params)                  { this{"Anonymous Cluster", preemption_rate, 1, io_params}; }
static inline void ?{} (cluster & this, const char name[], const io_context_params & io_params)                         { this{name, default_preemption(), 1, io_params}; }
static inline void ?{} (cluster & this, unsigned num_io, const io_context_params & io_params)                           { this{"Anonymous Cluster", default_preemption(), num_io, io_params}; }
static inline void ?{} (cluster & this, Duration preemption_rate, unsigned num_io, const io_context_params & io_params) { this{"Anonymous Cluster", preemption_rate, num_io, io_params}; }
static inline void ?{} (cluster & this, const char name[], unsigned num_io, const io_context_params & io_params)        { this{name, default_preemption(), num_io, io_params}; }

static inline [cluster *&, cluster *& ] __get( cluster & this ) __attribute__((const)) { return this.node.[next, prev]; }

static inline struct processor * active_processor() { return publicTLS_get( this_processor ); } // UNSAFE
static inline struct cluster   * active_cluster  () { return publicTLS_get( this_processor )->cltr; }

#if !defined(__CFA_NO_STATISTICS__)
	void print_stats_now( cluster & this, int flags );

	static inline void print_stats_at_exit( cluster & this, int flags ) {
		this.print_stats |= flags;
	}

	static inline void print_stats_at_exit( processor & this, int flags ) {
		this.print_stats |= flags;
	}

	void print_halts( processor & this );
#endif

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