234 lines
		
	
	
		
			7.0 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			234 lines
		
	
	
		
			7.0 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/************************************************************************
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**                                                                     **
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**                   The YapTab/YapOr/OPTYap systems                   **
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**                                                                     **
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** YapTab extends the Yap Prolog engine to support sequential tabling  **
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** YapOr extends the Yap Prolog engine to support or-parallelism       **
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** OPTYap extends the Yap Prolog engine to support or-parallel tabling **
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**                                                                     **
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**                                                                     **
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**      Yap Prolog was developed at University of Porto, Portugal      **
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**                                                                     **
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************************************************************************/
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/* ------------------ **
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**      Includes      **
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** ------------------ */
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#include "Yap.h"
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#ifdef YAPOR_COW
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#include <sys/types.h>
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#include <unistd.h>
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#include <stdio.h>
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#include "Yatom.h"
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#include "YapHeap.h"
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#include "or.macros.h"
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/* ------------------------------------- **
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**      Local functions declaration      **
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** ------------------------------------- */
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static void share_private_nodes(int worker_q);
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/* ----------------------- **
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**      Local inlines      **
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** ----------------------- */
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static inline void PUT_BUSY(int);
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static inline
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void PUT_BUSY(int worker_num) {
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  LOCK(GLOBAL_locks_bm_idle_workers);
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  BITMAP_delete(GLOBAL_bm_idle_workers, worker_num);
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  UNLOCK(GLOBAL_locks_bm_idle_workers);
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  return;
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}
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/* -------------------------- **
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**      Global functions      **
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** -------------------------- */
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void make_root_choice_point(void) {
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  if (worker_id == 0) {
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    LOCAL_top_cp = GLOBAL_root_cp = OrFr_node(GLOBAL_root_or_fr) = B;
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  } else {
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    B = LOCAL_top_cp = GLOBAL_root_cp;
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    B->cp_tr = TR = ((choiceptr) (worker_offset(0) + (CELL)(B)))->cp_tr;
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  }
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  B->cp_h = H0;
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  B->cp_ap = GETWORK;
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  B->cp_or_fr = GLOBAL_root_or_fr;
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  LOCAL_top_or_fr = GLOBAL_root_or_fr;
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  LOCAL_load = 0;
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  LOCAL_prune_request = NULL;
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  BRANCH(worker_id, 0) = 0;
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  return;
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}
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void free_root_choice_point(void) {
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  B = LOCAL_top_cp->cp_b;
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  LOCAL_top_cp = (choiceptr) LOCAL_LocalBase;
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  return;
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}
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int p_share_work(void) {
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  int worker_q = LOCAL_share_request;
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  int son;
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  if (! BITMAP_member(OrFr_members(REMOTE_top_or_fr(worker_q)), worker_id) ||
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      B == REMOTE_top_cp(worker_q) ||
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      (LOCAL_load <= GLOBAL_delayed_release_load && OrFr_nearest_livenode(LOCAL_top_or_fr) == NULL)) {
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    /* refuse sharing request */
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    REMOTE_reply_signal(LOCAL_share_request) = no_sharing;
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    LOCAL_share_request = MAX_WORKERS;
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    PUT_OUT_REQUESTABLE(worker_id);
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    return TRUE;
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  }
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  /* sharing request accepted */
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  REMOTE_reply_signal(worker_q) = sharing;
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  share_private_nodes(worker_q);
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  if ((son = fork()) == 0) {
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    worker_id = worker_q;  /* child becomes requesting worker */
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    LOCAL = REMOTE(worker_id);
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    LOCAL_reply_signal = worker_ready;
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    PUT_IN_REQUESTABLE(worker_id);
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    PUT_BUSY(worker_id);
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    return FALSE;
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  } else {
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    GLOBAL_worker_pid(worker_q) = son;
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    LOCAL_share_request = MAX_WORKERS;
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    PUT_IN_REQUESTABLE(worker_id);
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    return TRUE;
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  }
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}
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int q_share_work(int worker_p) {
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  LOCK_OR_FRAME(LOCAL_top_or_fr);
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  if (Get_REMOTE_prune_request(worker_p)) {
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    /* worker p with prune request */
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    UNLOCK_OR_FRAME(LOCAL_top_or_fr);
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    return FALSE;
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  }
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  YAPOR_ERROR_CHECKING(q_share_work, OrFr_pend_prune_cp(LOCAL_top_or_fr) && BRANCH_LTT(worker_p, OrFr_depth(LOCAL_top_or_fr)) < OrFr_pend_prune_ltt(LOCAL_top_or_fr));
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  /* there is no pending prune with worker p at right --> safe move to worker p branch */
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  BRANCH(worker_id, OrFr_depth(LOCAL_top_or_fr)) = BRANCH(worker_p, OrFr_depth(LOCAL_top_or_fr));
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  LOCAL_prune_request = NULL;
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  UNLOCK_OR_FRAME(LOCAL_top_or_fr);
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  /* make sharing request */
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  LOCK_WORKER(worker_p);
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  if (BITMAP_member(GLOBAL_bm_idle_workers, worker_p) || 
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      REMOTE_share_request(worker_p) != MAX_WORKERS) {
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    /* worker p is idle or has another request */
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    UNLOCK_WORKER(worker_p);
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    return FALSE;
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  }
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  REMOTE_share_request(worker_p) = worker_id;
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  UNLOCK_WORKER(worker_p);
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  /* wait for an answer */
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  while (LOCAL_reply_signal == worker_ready);
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  if (LOCAL_reply_signal == no_sharing) {
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    /* sharing request refused */
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    LOCAL_reply_signal = worker_ready;
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    return FALSE;
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  }
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  /* exit this process */
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  exit(0);
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}
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/* ------------------------- **
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**      Local functions      **
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** ------------------------- */
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static
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void share_private_nodes(int worker_q) {
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  int depth;
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  choiceptr AuxB;
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  or_fr_ptr or_frame, previous_or_frame;
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  /* initialize auxiliary variables */
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  AuxB = B;
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  previous_or_frame = NULL;
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  depth = OrFr_depth(LOCAL_top_or_fr);
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  /* sharing loop */
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  while (AuxB != LOCAL_top_cp) {
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    depth++;
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    ALLOC_OR_FRAME(or_frame);
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    INIT_LOCK(OrFr_lock(or_frame));
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    SetOrFr_node(or_frame, AuxB);
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    OrFr_alternative(or_frame) = AuxB->cp_ap;
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    OrFr_pend_prune_cp(or_frame) = NULL;
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    OrFr_nearest_leftnode(or_frame) = LOCAL_top_or_fr;
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    OrFr_qg_solutions(or_frame) = NULL;
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    BITMAP_clear(OrFr_members(or_frame));
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    BITMAP_insert(OrFr_members(or_frame), worker_id);
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    BITMAP_insert(OrFr_members(or_frame), worker_q);
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    if (AuxB->cp_ap && YAMOP_SEQ(AuxB->cp_ap)) {
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      AuxB->cp_ap = GETWORK_SEQ;
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    } else {
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      AuxB->cp_ap = GETWORK;
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    }
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    AuxB->cp_or_fr = or_frame;
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    AuxB = AuxB->cp_b;
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    if (previous_or_frame) {
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      OrFr_nearest_livenode(previous_or_frame) = OrFr_next(previous_or_frame) = or_frame;
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    }
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    previous_or_frame = or_frame;
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  }
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  /* initialize last or-frame pointer */
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  or_frame = AuxB->cp_or_fr;
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  if (previous_or_frame) {
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    OrFr_nearest_livenode(previous_or_frame) = OrFr_next(previous_or_frame) = or_frame;
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  }
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  /* update depth */
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  if (depth >= MAX_BRANCH_DEPTH)
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    Yap_Error(INTERNAL_ERROR, TermNil, "maximum depth exceded (share_private_nodes)");
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  or_frame = B->cp_or_fr;
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  while (or_frame != LOCAL_top_or_fr) {
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    unsigned int branch;
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    if (OrFr_alternative(or_frame)) {
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      branch = YAMOP_OR_ARG(OrFr_alternative(or_frame)) + 1;
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    } else {
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      branch = 1;
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    }
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    branch |= YAMOP_CUT_FLAG;  /* in doubt, assume cut */
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    BRANCH(worker_id, depth) = BRANCH(worker_q, depth) = branch;
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    OrFr_depth(or_frame) = depth--;
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    or_frame = OrFr_next_on_stack(or_frame);
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  }
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  /* update old shared nodes */
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  while (or_frame != REMOTE_top_or_fr(worker_q)) {
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    LOCK_OR_FRAME(or_frame);
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    BRANCH(worker_q, OrFr_depth(or_frame)) = BRANCH(worker_id, OrFr_depth(or_frame));
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    BITMAP_insert(OrFr_members(or_frame), worker_q);
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    UNLOCK_OR_FRAME(or_frame);
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    or_frame = OrFr_next_on_stack(or_frame);
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  }
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  /* update top shared nodes */
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  REMOTE_top_cp(worker_q) = LOCAL_top_cp = B;
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  REMOTE_top_or_fr(worker_q) = LOCAL_top_or_fr = LOCAL_top_cp->cp_or_fr;
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  /* update prune request */
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  if (LOCAL_prune_request) {
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    CUT_send_prune_request(worker_q, LOCAL_prune_request);
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  }
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  /* update load and return */
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  REMOTE_load(worker_q) = LOCAL_load = 0;
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  return;
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}
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#endif /* YAPOR_COW */
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