pipe_cache_policy.h

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/*
    This file is part of Ansel.
    Copyright (C) 2026 Aurélien Pierre.
    Copyright (C) 2026 Guillaume Stutin.
 
    Ansel is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    Ansel is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with Ansel.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#ifndef DT_DEVELOP_PIPE_CACHE_POLICY_H
#define DT_DEVELOP_PIPE_CACHE_POLICY_H
 
#include <glib.h>
 
#include "system/macros.h"   // IS_NULL_PTR
 
typedef struct dt_dev_pipe_cache_policy_inputs_t
{
  gboolean authored_cache;
  gboolean user_requested_cache;
  gboolean supports_opencl;
  gboolean color_picker_on;
  gboolean global_hist_output_on;
  gboolean global_hist_input_on;
  gboolean module_hist_on;
  gboolean active_in_gui;
  gboolean has_autoset;
} dt_dev_pipe_cache_policy_inputs_t;
 
static inline gboolean dt_dev_pipe_cache_policy_decide(const dt_dev_pipe_cache_policy_inputs_t *in,
                                                       const gboolean inherited_requirement,
                                                       gboolean *upstream_requirement)
{
  // What THIS node needs from the node before it.
  const gboolean own_input_requirement
      = !in->supports_opencl || in->active_in_gui || in->module_hist_on
        || in->global_hist_input_on || in->has_autoset;
 
  // ONE HOP, not transitive. A node's output must reach host RAM when the node that CONSUMES
  // it reads from RAM -- and that says nothing about the node before it, which publishes to a
  // consumer of its own. Carried further up (`own || inherited'), the requirement would be
  // monotone: the seal seeds the walk with TRUE for the displayed final output, so every
  // enabled node would copy its whole output device->host on every frame.
  //
  // A stale host copy is no reason to carry the requirement further: the staleness lives in the
  // cacheline, and the cache handles it there. A line rekeyed in place reports no host pixels
  // (dt_pixel_cache_entry_t.host_stale) until they are rewritten for its new hash.
  if(!IS_NULL_PTR(upstream_requirement))
    *upstream_requirement = own_input_requirement;
 
  return in->authored_cache || in->user_requested_cache || in->color_picker_on
         || in->global_hist_output_on || inherited_requirement;
}
 
#endif // DT_DEVELOP_PIPE_CACHE_POLICY_H
 
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