From 4cd08f0ef91d429586bc2c0228eaefffab91c342 Mon Sep 17 00:00:00 2001
From: Leonid Yuriev <leo@yuriev.ru>
Date: Sat, 21 Nov 2020 17:53:17 +0300
Subject: [PATCH] mdbx: add `MDBX_opt_rp_augment_limit`.

More for https://github.com/erthink/libmdbx/issues/128

Change-Id: I94f3350b72ad11d0b586aaef1574f7654223bc40
---
 mdbx.h          |  4 ++++
 src/core.c      | 14 ++++++++++++--
 src/internals.h |  1 +
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/mdbx.h b/mdbx.h
index 19c7cec3..7fa59a4c 100644
--- a/mdbx.h
+++ b/mdbx.h
@@ -1802,6 +1802,10 @@ enum MDBX_option_t {
 
   /** \brief The limit to grow a list of pre-allocated dirty pages. */
   MDBX_opt_dp_reserve_limit,
+
+  /** \brief The limit to grow a list of reclaimed pages
+   * for finding a sequence of contiguous pages. */
+  MDBX_opt_rp_augment_limit,
 };
 #ifndef __cplusplus
 /** \ingroup c_settings */
diff --git a/src/core.c b/src/core.c
index 3a17245f..a5ea7ee5 100644
--- a/src/core.c
+++ b/src/core.c
@@ -5278,9 +5278,8 @@ skip_cache:
       }
       const unsigned gc_len = MDBX_PNL_SIZE(gc_pnl);
       /* TODO: provide a user-configurable threshold */
-      const unsigned threshold_2_stop_gc_reclaiming = MDBX_PNL_MAX / 4;
       if (unlikely(gc_len + MDBX_PNL_SIZE(txn->tw.reclaimed_pglist) >
-                   threshold_2_stop_gc_reclaiming) &&
+                   env->me_options.rp_augment_limit) &&
           (pgno_add(txn->mt_next_pgno, num) <= txn->mt_geo.upper ||
            gc_len + MDBX_PNL_SIZE(txn->tw.reclaimed_pglist) >=
                MDBX_PNL_MAX / 16 * 15)) {
@@ -9234,6 +9233,7 @@ __cold int mdbx_env_create(MDBX_env **penv) {
   env->me_stuck_meta = -1;
 
   env->me_options.dp_reserve_limit = 1024;
+  env->me_options.rp_augment_limit = 1024 * 1024;
 
   int rc;
   const size_t os_psize = mdbx_syspagesize();
@@ -19710,6 +19710,12 @@ __cold int mdbx_env_set_option(MDBX_env *env, const MDBX_option_t option,
     }
     break;
 
+  case MDBX_opt_rp_augment_limit:
+    if (unlikely(value > MDBX_PNL_MAX))
+      return MDBX_EINVAL;
+    env->me_options.rp_augment_limit = (unsigned)value;
+    break;
+
   default:
     return MDBX_EINVAL;
   }
@@ -19752,6 +19758,10 @@ __cold int mdbx_env_get_option(const MDBX_env *env, const MDBX_option_t option,
     *value = env->me_options.dp_reserve_limit;
     break;
 
+  case MDBX_opt_rp_augment_limit:
+    *value = env->me_options.rp_augment_limit;
+    break;
+
   default:
     return MDBX_EINVAL;
   }
diff --git a/src/internals.h b/src/internals.h
index 29ee6d86..2d640b85 100644
--- a/src/internals.h
+++ b/src/internals.h
@@ -995,6 +995,7 @@ struct MDBX_env {
   unsigned me_dp_reserve_len;
   struct {
     unsigned dp_reserve_limit;
+    unsigned rp_augment_limit;
   } me_options;
   struct {
 #if MDBX_LOCKING > 0