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+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2018. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * %CopyrightEnd%
+ */
+
+/*
+ * Description: Process signal queue implementation.
+ *
+ * Currently the following signals are handled:
+ * - Messages
+ * - Exit
+ * - Monitor
+ * - Demonitor
+ * - Monitor down
+ * - Persistent monitor message
+ * - Link
+ * - Unlink
+ * - Group leader
+ * - Is process alive
+ * - Process info request
+ * - Suspend request (monitor of suspend type)
+ * - Resume request (demonitor of suspend type)
+ * - Suspend cleanup (monitor down of suspend type)
+ * - Sync suspend
+ * - RPC request
+ * - Trace change
+ *
+ * The signal queue consists of three parts:
+ * - Outer queue (sig_inq field in process struct)
+ * - Middle queue (sig_qs field in process struct)
+ * - Inner queue (sig_qs field in process struct)
+ *
+ * Incoming signals are placed in the outer queue
+ * by other processes, ports, or by the runtime system
+ * itself. This queue is protected by the msgq process
+ * lock and may be accessed by any other entity. While
+ * a signal is located in the outer queue, it is still
+ * in transit between sender and receiver.
+ *
+ * The middle and the inner queues are private to the
+ * receiving process and can only be accessed while
+ * holding the main process lock. The signal changes
+ * from being in transit to being received while in
+ * the middle queue. Non-message signals are handled
+ * immediately upon reception while message signals
+ * are moved into the inner queue.
+ *
+ * In the outer and middle queues both message signals
+ * and non-message signals are mixed. Signals in these
+ * queues are referenced using two single linked lists.
+ * One single linked list that go through all signals
+ * in the queue and another single linked list that
+ * goes through only non-message signals. The list
+ * through the non-message signals is used for fast
+ * access to these signals in the middle queue, since
+ * these should be handled immediately upon reception.
+ *
+ * The inner queue consists only of one single linked
+ * list through the message signals. A receive
+ * expression can only operate on messages once they
+ * have entered the inner queue.
+ *
+ * Author: Rickard Green
+ */
+
+#ifndef ERTS_PROC_SIG_QUEUE_H_TYPE__
+#define ERTS_PROC_SIG_QUEUE_H_TYPE__
+
+#if 0
+# define ERTS_PROC_SIG_HARD_DEBUG
+#endif
+#if 0
+# define ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+#endif
+
+struct erl_mesg;
+
+typedef struct {
+ struct erl_mesg *next;
+ union {
+ struct erl_mesg **next;
+ void *attachment;
+ } specific;
+ Eterm tag;
+} ErtsSignalCommon;
+
+#define ERTS_SIG_HANDLE_REDS_MAX_PREFERED (CONTEXT_REDS/40)
+
+#ifdef ERTS_PROC_SIG_HARD_DEBUG
+# define ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE(P) \
+ ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE__((P), "")
+# define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(P, QL) \
+ ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__((P), (QL), "")
+# define ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE__(P, What) \
+ erts_proc_sig_hdbg_check_in_queue((P), (What), __FILE__, __LINE__)
+# define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__(P, QL, What) \
+ erts_proc_sig_hdbg_check_priv_queue((P), (QL), (What), __FILE__, __LINE__)
+struct process;
+void erts_proc_sig_hdbg_check_priv_queue(struct process *c_p, int qlock,
+ char *what, char *file, int line);
+void erts_proc_sig_hdbg_check_in_queue(struct process *c_p, char *what,
+ char *file, int line);
+#else
+# define ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE(P)
+# define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(P, QL)
+# define ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE__(P, What)
+#define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__(P, QL, What)
+#endif
+
+#endif
+
+#if !defined(ERTS_PROC_SIG_QUEUE_H__) && !defined(ERTS_PROC_SIG_QUEUE_TYPE_ONLY)
+#define ERTS_PROC_SIG_QUEUE_H__
+
+#define ERTS_SIG_Q_OP_BITS 8
+#define ERTS_SIG_Q_OP_SHIFT 0
+#define ERTS_SIG_Q_OP_MASK ((1 << ERTS_SIG_Q_OP_BITS) - 1)
+
+#define ERTS_SIG_Q_TYPE_BITS 8
+#define ERTS_SIG_Q_TYPE_SHIFT ERTS_SIG_Q_OP_BITS
+#define ERTS_SIG_Q_TYPE_MASK ((1 << ERTS_SIG_Q_TYPE_BITS) - 1)
+
+#define ERTS_SIG_Q_NON_X_BITS__ (_HEADER_ARITY_OFFS \
+ + ERTS_SIG_Q_OP_BITS \
+ + ERTS_SIG_Q_TYPE_BITS)
+
+#define ERTS_SIG_Q_XTRA_BITS (32 - ERTS_SIG_Q_NON_X_BITS__)
+#define ERTS_SIG_Q_XTRA_SHIFT (ERTS_SIG_Q_OP_BITS \
+ + ERTS_SIG_Q_TYPE_BITS)
+#define ERTS_SIG_Q_XTRA_MASK ((1 << ERTS_SIG_Q_XTRA_BITS) - 1)
+
+
+#define ERTS_PROC_SIG_OP(Tag) \
+ ((int) (_unchecked_thing_arityval((Tag)) \
+ >> ERTS_SIG_Q_OP_SHIFT) & ERTS_SIG_Q_OP_MASK)
+
+#define ERTS_PROC_SIG_TYPE(Tag) \
+ ((Uint16) (_unchecked_thing_arityval((Tag)) \
+ >> ERTS_SIG_Q_TYPE_SHIFT) & ERTS_SIG_Q_TYPE_MASK)
+
+#define ERTS_PROC_SIG_XTRA(Tag) \
+ ((Uint32) (_unchecked_thing_arityval((Tag)) \
+ >> ERTS_SIG_Q_XTRA_SHIFT) & ERTS_SIG_Q_XTRA_MASK)
+
+#define ERTS_PROC_SIG_MAKE_TAG(Op, Type, Xtra) \
+ (ASSERT(0 <= (Xtra) && (Xtra) <= ERTS_SIG_Q_XTRA_MASK), \
+ _make_header((((Type) & ERTS_SIG_Q_TYPE_MASK) \
+ << ERTS_SIG_Q_TYPE_SHIFT) \
+ | (((Op) & ERTS_SIG_Q_OP_MASK) \
+ << ERTS_SIG_Q_OP_SHIFT) \
+ | (((Xtra) & ERTS_SIG_Q_XTRA_MASK) \
+ << ERTS_SIG_Q_XTRA_SHIFT), \
+ _TAG_HEADER_EXTERNAL_PID))
+
+
+/*
+ * ERTS_SIG_Q_OP_MSGQ_LEN_OFFS_MARK is not an actual
+ * operation. We keep it at the top of the OP range,
+ * larger than ERTS_SIG_Q_OP_MAX.
+ */
+#define ERTS_SIG_Q_OP_MSGQ_LEN_OFFS_MARK ERTS_SIG_Q_OP_MASK
+
+#define ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK \
+ ERTS_PROC_SIG_MAKE_TAG(ERTS_SIG_Q_OP_MSGQ_LEN_OFFS_MARK,0,0)
+
+struct dist_entry_;
+
+/*
+ * Send operations of currently supported process signals follow...
+ */
+
+/**
+ *
+ * @brief Send an exit signal to a process.
+ *
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[in] from Identifier of sender.
+ *
+ * @param[in] to Identifier of local process
+ * to send signal to.
+ *
+ * @param[in] reason Exit reason.
+ *
+ * @param[in] token Seq trace token.
+ *
+ * @param[in] normal_kills If non-zero, also normal exit
+ * reason will kill the receiver
+ * if it is not trapping exit.
+ *
+ */
+void
+erts_proc_sig_send_exit(Process *c_p, Eterm from, Eterm to,
+ Eterm reason, Eterm token, int normal_kills);
+
+/**
+ *
+ * @brief Send an exit signal due to broken link to a process.
+ *
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[in] from Identifier of sender.
+ *
+ * @param[in] lnk Pointer to link structure
+ * from the sending side. It
+ * should contain information
+ * about receiver.
+ *
+ * @param[in] reason Exit reason.
+ *
+ * @param[in] token Seq trace token.
+ *
+ */
+void
+erts_proc_sig_send_link_exit(Process *c_p, Eterm from, ErtsLink *lnk,
+ Eterm reason, Eterm token);
+
+/**
+ *
+ * @brief Send an link signal to a process.
+ *
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] lnk Pointer to link structure to
+ * insert on receiver side.
+ *
+ * @return A non-zero value if
+ * signal was successfully
+ * sent. If a zero, value
+ * the signal was not sent
+ * due to the receiver not
+ * existing. The sender
+ * needs to deallocate the
+ * link structure.
+ *
+ */
+int
+erts_proc_sig_send_link(Process *c_p, Eterm to, ErtsLink *lnk);
+
+/**
+ *
+ * @brief Send an unlink signal to a process.
+ *
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[in] lnk Pointer to link structure from
+ * the sending side. It should
+ * contain information about
+ * receiver.
+ */
+void
+erts_proc_sig_send_unlink(Process *c_p, ErtsLink *lnk);
+
+/**
+ *
+ * @brief Send an exit signal due to broken link to a process.
+ *
+ * This function is used instead of erts_proc_sig_send_link_exit()
+ * when the signal arrives via the distribution and
+ * no link structure is available.
+ *
+ * @param[in] dep Distribution entry of channel
+ * that the signal arrived on.
+ *
+ * @param[in] from Identifier of sender.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] reason Exit reason.
+ *
+ * @param[in] token Seq trace token.
+ *
+ */
+void
+erts_proc_sig_send_dist_link_exit(struct dist_entry_ *dep,
+ Eterm from, Eterm to,
+ Eterm reason, Eterm token);
+
+/**
+ *
+ * @brief Send an unlink signal to a process.
+ *
+ * This function is used instead of erts_proc_sig_send_unlink()
+ * when the signal arrives via the distribution and
+ * no link structure is available.
+ *
+ * @param[in] dep Distribution entry of channel
+ * that the signal arrived on.
+ *
+ * @param[in] from Identifier of sender.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ */
+void
+erts_proc_sig_send_dist_unlink(struct dist_entry_ *dep,
+ Eterm from, Eterm to);
+
+/**
+ *
+ * @brief Send a monitor down signal to a process.
+ *
+ * @param[in] mon Pointer to target monitor
+ * structure from the sending
+ * side. It should contain
+ * information about receiver.
+ *
+ * @param[in] reason Exit reason.
+ *
+ */
+void
+erts_proc_sig_send_monitor_down(ErtsMonitor *mon, Eterm reason);
+
+/**
+ *
+ * @brief Send a demonitor signal to a process.
+ *
+ * @param[in] mon Pointer to origin monitor
+ * structure from the sending
+ * side. It should contain
+ * information about receiver.
+ *
+ * @param[in] reason Exit reason.
+ *
+ */
+void
+erts_proc_sig_send_demonitor(ErtsMonitor *mon);
+
+/**
+ *
+ * @brief Send a monitor signal to a process.
+ *
+ * @param[in] mon Pointer to target monitor
+ * structure to insert on
+ * receiver side.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @return A non-zero value if
+ * signal was successfully
+ * sent. If a zero, value
+ * the signal was not sent
+ * due to the receiver not
+ * existing. The sender
+ * needs to deallocate the
+ * monitor structure.
+ *
+ */
+int
+erts_proc_sig_send_monitor(ErtsMonitor *mon, Eterm to);
+
+/**
+ *
+ * @brief Send a monitor down signal to a process.
+ *
+ * This function is used instead of erts_proc_sig_send_monitor_down()
+ * when the signal arrives via the distribution and
+ * no link structure is available.
+ *
+ * @param[in] dep Pointer to distribution entry
+ * of channel that the signal
+ * arrived on.
+ *
+ * @param[in] ref Reference identifying the monitor.
+ *
+ * @param[in] from Identifier of sender.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] reason Exit reason.
+ *
+ */
+void
+erts_proc_sig_send_dist_monitor_down(DistEntry *dep, Eterm ref,
+ Eterm from, Eterm to,
+ Eterm reason);
+
+/**
+ *
+ * @brief Send a demonitor signal to a process.
+ *
+ * This function is used instead of erts_proc_sig_send_demonitor()
+ * when the signal arrives via the distribution and
+ * no monitor structure is available.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] ref Reference identifying the monitor.
+ *
+ */
+void
+erts_proc_sig_send_dist_demonitor(Eterm to, Eterm ref);
+
+/**
+ *
+ * @brief Send a persistent monitor triggered signal to a process.
+ *
+ * Used by monitors that are not auto disabled such as for
+ * example 'time_offset' monitors.
+ *
+ * @param[in] type Monitor type.
+ *
+ * @param[in] key Monitor key.
+ *
+ * @param[in] from Identifier of sender.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] msg Message template.
+ *
+ * @param[in] msg_sz Heap size of message template.
+ *
+ */
+void
+erts_proc_sig_send_persistent_monitor_msg(Uint16 type, Eterm key,
+ Eterm from, Eterm to,
+ Eterm msg, Uint msg_sz);
+
+/**
+ *
+ * @brief Send a trace change signal to a process.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] on Trace flags to enable.
+ *
+ * @param[in] off Trace flags to disable.
+ *
+ * @param[in] tracer Tracer to set. If the non-value,
+ * tracer will not be changed.
+ *
+ */
+void
+erts_proc_sig_send_trace_change(Eterm to, Uint on, Uint off,
+ Eterm tracer);
+
+/**
+ *
+ * @brief Send a group leader signal to a process.
+ *
+ * Set group-leader of receiving process. If sent locally,
+ * a response message '{Ref, Result}' is sent to the original
+ * sender when performed where Ref is the reference passed
+ * as 'ref' argument, and Result is either 'true' or 'badarg'.
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ * NULL if signal arrived via
+ * distribution.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] gl Identifier of new group leader.
+ *
+ * @param[in] ref Reference to use in response
+ * message to locally sending
+ * process (i.e., c_p when c_p
+ * is non-null).
+ *
+ */
+void
+erts_proc_sig_send_group_leader(Process *c_p, Eterm to, Eterm gl,
+ Eterm ref);
+
+/**
+ *
+ * @brief Send an 'is process alive' signal to a process.
+ *
+ * A response message '{Ref, Result}' is sent to the
+ * sender when performed where Ref is the reference passed
+ * as 'ref' argument, and Result is either 'true' or 'false'.
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ * NULL if signal arrived via
+ * distribution.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] ref Reference to use in response
+ * message to the sending
+ * process (i.e., c_p).
+ *
+ */
+void
+erts_proc_sig_send_is_alive_request(Process *c_p, Eterm to,
+ Eterm ref);
+
+/**
+ *
+ * @brief Send a 'process info request' signal to a process.
+ *
+ * A response message '{Ref, Result}' is sent to the
+ * sender when performed where Ref is the reference passed
+ * as 'ref' argument, and Result corresponds to return result
+ * from erlang:process_info/[1,2].
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ * NULL if signal arrived via
+ * distribution.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] item_ix Info index array to pass to
+ * erts_process_info()
+ *
+ * @param[in] len Lenght of info index array
+ *
+ * @param[in] need_msgq_len Non-zero if message queue
+ * length is needed; otherwise,
+ * zero. If non-zero, sig_qs.len
+ * will be set to correspond
+ * to the message queue length
+ * before call to
+ * erts_process_info()
+ *
+ * @param[in] flags Flags to pass to
+ * erts_process_info()
+ *
+ * @param[in] reserve_size Heap size that is known to
+ * be needed. May not be correct
+ * though.
+ *
+ * @param[in] ref Reference to use in response
+ * message to the sending
+ * process (i.e., c_p).
+ *
+ */
+int
+erts_proc_sig_send_process_info_request(Process *c_p,
+ Eterm to,
+ int *item_ix,
+ int len,
+ int need_msgq_len,
+ int flags,
+ Uint reserve_size,
+ Eterm ref);
+
+/**
+ *
+ * @brief Send a 'sync suspend' signal to a process.
+ *
+ * A response message '{Tag, Reply}' is sent to the
+ * sender when performed where Tag is the term passed
+ * as 'tag' argument. Reply is either 'suspended',
+ * 'not_suspended', 'exited' if the operation is
+ * asynchronous; otherwise, the 'reply' argument or
+ * 'badarg' if process terminated.
+ *
+ * This signal does *not* change the suspend state, only
+ * reads and reply the state. This signal is typically
+ * sent after a suspend request (monitor of suspend type)
+ * signal has been sent to the process in order to get a
+ * response when the suspend monitor has been processed.
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[in] to Identifier of receiver.
+ *
+ * @param[in] tag Tag to use in response
+ * message to the sending
+ * process (i.e., c_p).
+ *
+ * @param[in] reply Reply to send if this
+ * is a synchronous operation;
+ * otherwise, THE_NON_VALUE.
+ */
+void
+erts_proc_sig_send_sync_suspend(Process *c_p, Eterm to,
+ Eterm tag, Eterm reply);
+
+/**
+ *
+ * @brief Send an 'rpc' signal to a process.
+ *
+ * The function 'func' will be executed in the
+ * context of the receiving process. A response
+ * message '{Ref, Result}' is sent to the sender
+ * when 'func' has been called. 'Ref' is the reference
+ * returned by this function and 'Result' is the
+ * term returned by 'func'. If the return value of
+ * 'func' is not an immediate term, 'func' has to
+ * allocate a heap fragment where the result is stored
+ * and update the the heap fragment pointer pointer
+ * passed as third argument to point to it.
+ *
+ * If this function returns a reference, 'func' will
+ * be called in the context of the receiver. However,
+ * note that this might happen when the receiver is in
+ * an exiting state. The caller of this function
+ * *unconditionally* has to enter a receive that match
+ * on the returned reference in all clauses as next
+ * receive; otherwise, bad things will happen!
+ *
+ * If THE_NON_VALUE is returned, the receiver did not
+ * exist. The signal was not sent, and no specific
+ * receive has to be entered by the caller.
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[in] to Identifier of receiver process.
+ *
+ * @param[in] reply Non-zero if a reply is wanted.
+ *
+ * @param[in] func Function to execute in the
+ * context of the receiver.
+ * First argument will be a
+ * pointer to the process struct
+ * of the receiver process.
+ * Second argument will be 'arg'
+ * (see below). Third argument
+ * will be a pointer to a pointer
+ * to a heap fragment for storage
+ * of result returned from 'func'
+ * (i.e. an 'out' parameter).
+ *
+ * @param[in] arg Void pointer to argument
+ * to pass as second argument
+ * in call of 'func'.
+ *
+ * @returns If the request was sent,
+ * an internal ordinary
+ * reference; otherwise,
+ * THE_NON_VALUE (non-existing
+ * receiver).
+ */
+Eterm
+erts_proc_sig_send_rpc_request(Process *c_p,
+ Eterm to,
+ int reply,
+ Eterm (*func)(Process *, void *, int *, ErlHeapFragment **),
+ void *arg);
+
+/*
+ * End of send operations of currently supported process signals.
+ */
+
+
+/**
+ *
+ * @brief Handle incoming signals.
+ *
+ * Called by an ordinary scheduler in order to handle incoming
+ * signals for a process. The work is done on the middle part
+ * of the signal queue. The maximum amount of signals handled
+ * is limited by the amount of reductions given when calling.
+ * Note that a reduction does not necessarily map to a signal.
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[out] statep Pointer to process state after
+ * signal handling. May not be NULL.
+ *
+ * @param[in,out] redsp Pointer to an integer containing
+ * reductions. On input, the amount
+ * of preferred reductions to be
+ * used by the call. On output, the
+ * amount of reductions consumed.
+ *
+ * @param[in] max_reds Absolute maximum of reductions
+ * to use. If the process cannot
+ * make progress after the preferred
+ * amount of reductions has been
+ * consumed, signal handling may
+ * proceed up to a maximum of
+ * 'max_reds' in order to make
+ * the process able to proceed
+ * with other tasks after handling
+ * has finished.
+ *
+ * @param[in] local_only If is zero, new signals may be
+ * fetched from the outer queue and
+ * put in the middle queue before
+ * signal handling is performed. If
+ * non-zero, no new signals will be
+ * fetched before handling begins.
+ *
+ * @return Returns a non-zero value, when
+ * no more signals to handle in the
+ * middle queue remain. A zero
+ * return value means that there
+ * remains signals in the middle
+ * queue.
+ */
+int
+erts_proc_sig_handle_incoming(Process *c_p, erts_aint32_t *statep,
+ int *redsp, int max_reds,
+ int local_only);
+
+/**
+ *
+ * @brief Handle remaining signals for an exiting process
+ *
+ * Called as part of termination of a process. It will handle
+ * remaining signals.
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[in,out] redsp Pointer to an integer containing
+ * reductions. On input, the amount
+ * of maximum reductions to be
+ * used by the call. On output, the
+ * amount of reductions consumed.
+ *
+ * @return Returns a non-zero value, when
+ * no more signals to handle in the
+ * middle queue remain. A zero
+ * return value means that there
+ * remains signals in the middle
+ * queue.
+ */
+int
+erts_proc_sig_handle_exit(Process *c_p, int *redsp);
+
+/**
+ *
+ * @brief Helper for loop_rec instruction.
+ *
+ * This function should only be called from the loop_rec
+ * instruction (or equivalents). It is called when loop_rec
+ * reach the end of the inner queue (which is the only
+ * part of the signal queue that receive is allowed to
+ * operate on). When called, this function tries to make
+ * more messages available in the inner queue. This by
+ * fetching signals from the outer queue to the middle
+ * queue and/or processing signals in the middle queue.
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[in] fcalls Content of FCALLS in
+ * process_main()
+ *
+ * @param[in] neg_o_reds Content of neg_o_reds in
+ * process_main()
+ *
+ * @param[out] msgpp Pointer to pointer to next
+ * available message to process.
+ * If *msgpp == NULL, no more
+ * messages are available.
+ *
+ * @param[out] get_outp Pointer to an integer
+ * indicating how to respond
+ * if no more messages are
+ * available (msgpp). If integer
+ * is set to zero, loop_rec
+ * should jump to an appropriate
+ * wait instruction. If zero,
+ * the message queue lock remain
+ * locked since the test for
+ * more messages was done.
+ * If the integer is set to a
+ * value larger that zero, the
+ * process exited. If the integer
+ * is set to a value less than
+ * zero, the process is required
+ * to yield.
+ *
+ *
+ * @return The amount of reductions
+ * consumed.
+ *
+ */
+int
+erts_proc_sig_receive_helper(Process *c_p, int fcalls,
+ int neg_o_reds, ErtsMessage **msgpp,
+ int *get_outp);
+
+/**
+ *
+ * @brief Fetch signals from the outer queue
+ *
+ * Fetches signals from outer queue and places them in the
+ * middle queue ready for signal handling. If the middle
+ * queue is empty, only message signals were present in the
+ * outer queue, and no receive tracing has been enabled on
+ * the process, the middle queue is bypassed and messages
+ * are delivered directly to the inner queue instead.
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ * @returns Amount of message signals in
+ * inner plus middle signal
+ * queues after fetch completed
+ * (NOT the message queue
+ * length).
+ */
+ERTS_GLB_INLINE Sint erts_proc_sig_fetch(Process *p);
+
+/**
+ *
+ * @brief Get amount of messages in private queues
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @returns Amount of message signals in
+ * inner plus middle signal
+ * queues after fetch completed
+ * (NOT the message queue
+ * length).
+ */
+Sint
+erts_proc_sig_privqs_len(Process *c_p);
+
+
+/**
+ * @brief Enqueue list of signals on process.
+ *
+ * Message queue must be locked on receiving process.
+ *
+ * @param rp Receiving process.
+ * @param first First signal in list.
+ * @param last Last signal in list.
+ * @param last_next Pointer to next-pointer to last non-message signal
+ * or NULL if no non-message signal after 'first'.
+ * @param msg_cnt Number of message signals in list.
+ * @param in_state 'state' of rp.
+ *
+ * @return 'state' of rp.
+ */
+erts_aint32_t
+erts_enqueue_signals(Process *rp, ErtsMessage *first,
+ ErtsMessage **last, ErtsMessage **last_next,
+ Uint msg_cnt,
+ erts_aint32_t in_state);
+
+/**
+ *
+ * @brief Flush pending signal.
+ *
+ */
+void
+erts_proc_sig_send_pending(ErtsSchedulerData* esdp);
+
+/**
+ *
+ * @brief Schedule process to handle enqueued signal(s).
+ *
+ * @param rp Receiving process.
+ * @param state 'state' of rp.
+ * @param enable_flag Additional state flags to enable, like
+ * ERTS_PSFLG_ACTIVE if message has been enqueued.
+ */
+ERTS_GLB_INLINE void erts_proc_notify_new_sig(Process* rp, erts_aint32_t state,
+ erts_aint32_t enable_flag);
+
+void erts_make_dirty_proc_handled(Eterm pid, erts_aint32_t state,
+ erts_aint32_t prio);
+
+
+typedef struct {
+ Uint size;
+ ErtsMessage *msgp;
+} ErtsMessageInfo;
+
+/**
+ *
+ * @brief Prepare signal queue for inspection by process_info()
+ *
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ * @param[in] rp Pointer to process struct of
+ * process to inspect.
+ *
+ * @param[in] rp_locks Process locks held on 'rp'.
+ *
+ * @param[in] info_on_self Integer set to non-zero value
+ * if caller is inspecting itself;
+ * otherwise, zero.
+ *
+ * @param[in] mip Pointer to array of
+ * ErtsMessageInfo structures.
+ */
+Uint erts_proc_sig_prep_msgq_for_inspection(Process *c_p,
+ Process *rp,
+ ErtsProcLocks rp_locks,
+ int info_on_self,
+ ErtsMessageInfo *mip);
+
+/**
+ *
+ * @brief Move message data of messages in private queues to heap
+ *
+ * Move message data of messages in private queues to the heap.
+ * This is part of GC of processes that uses on-heap message
+ * data.
+ *
+ * @param[in] c_p Pointer to process struct of
+ * currently executing process.
+ *
+ */
+void erts_proc_sig_move_msgs_to_heap(Process *c_p);
+
+/**
+ *
+ * @brief Size of signal in bytes.
+ *
+ * @param[in] sig Signal to inspect.
+ *
+ */
+Uint erts_proc_sig_signal_size(ErtsSignal *sig);
+
+
+/**
+ *
+ * @brief Clear seq trace tokens on all signals
+ *
+ * Assumes thread progress has been blocked!
+ *
+ * @param[in] c_p Pointer to process
+ *
+ */
+void
+erts_proc_sig_clear_seq_trace_tokens(Process *c_p);
+
+/**
+ *
+ * @brief Handle pending suspend requests
+ *
+ * Should be called by processes when they stop
+ * execution on a dirty scheduler if they have
+ * pending suspend requests (i.e. when
+ * ERTS_PROC_GET_PENDING_SUSPEND(c_p) != NULL).
+ *
+ * @param[in] c_p Pointer to executing
+ * process
+ */
+void
+erts_proc_sig_handle_pending_suspend(Process *c_p);
+
+/**
+ * @brief Initialize this functionality
+ */
+void erts_proc_sig_queue_init(void);
+
+void
+erts_proc_sig_debug_foreach_sig(Process *c_p,
+ void (*msg_func)(ErtsMessage *, void *),
+ void (*oh_func)(ErlOffHeap *, void *),
+ void (*mon_func)(ErtsMonitor *, void *),
+ void (*lnk_func)(ErtsLink *, void *),
+ void *arg);
+
+extern Process *erts_dirty_process_signal_handler;
+extern Process *erts_dirty_process_signal_handler_high;
+extern Process *erts_dirty_process_signal_handler_max;
+
+void erts_proc_sig_fetch__(Process *proc);
+Sint erts_proc_sig_fetch_msgq_len_offs__(Process *proc);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE Sint
+erts_proc_sig_fetch(Process *proc)
+{
+ Sint res = 0;
+ ErtsSignal *sig;
+
+ ERTS_LC_ASSERT(ERTS_PROC_IS_EXITING(proc)
+ || ((erts_proc_lc_my_proc_locks(proc)
+ & (ERTS_PROC_LOCK_MAIN
+ | ERTS_PROC_LOCK_MSGQ))
+ == (ERTS_PROC_LOCK_MAIN
+ | ERTS_PROC_LOCK_MSGQ)));
+
+ ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE(proc);
+ ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(proc, !0);
+
+ sig = (ErtsSignal *) proc->sig_inq.first;
+ if (sig) {
+ if (ERTS_LIKELY(sig->common.tag != ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK))
+ erts_proc_sig_fetch__(proc);
+ else
+ res = erts_proc_sig_fetch_msgq_len_offs__(proc);
+ }
+
+ res += proc->sig_qs.len;
+
+ ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(proc, !0);
+
+#ifdef ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+ {
+ Sint len = 0;
+ ERTS_FOREACH_SIG_PRIVQS(
+ proc, mp,
+ {
+ if (ERTS_SIG_IS_MSG(mp))
+ len++;
+ });
+ ERTS_ASSERT(res == len);
+ }
+#endif
+
+ return res;
+}
+
+ERTS_GLB_INLINE void
+erts_proc_notify_new_sig(Process* rp, erts_aint32_t state,
+ erts_aint32_t enable_flag)
+{
+ if (~(state & (ERTS_PSFLG_EXITING
+ | ERTS_PSFLG_ACTIVE_SYS
+ | ERTS_PSFLG_SIG_IN_Q))
+ | (~state & enable_flag)) {
+ /* Schedule process... */
+ state = erts_proc_sys_schedule(rp, state, enable_flag);
+ }
+
+ if (state & (ERTS_PSFLG_DIRTY_RUNNING
+ | ERTS_PSFLG_DIRTY_RUNNING_SYS)) {
+ erts_make_dirty_proc_handled(rp->common.id, state, -1);
+ }
+}
+
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
+#endif /* ERTS_PROC_SIG_QUEUE_H__ */