From 574106125f4f4003b45e8f7d60d200aa529b62f6 Mon Sep 17 00:00:00 2001
From: Olof hagsand <olof@hagsand.se>
Date: Wed, 6 Dec 2023 13:48:41 +0100
Subject: [PATCH] Added reference count for shared yang-specs (schema mounts)

---
 CHANGELOG.md                   |  4 +++
 lib/clixon/clixon_yang.h       |  3 ++
 lib/src/clixon_yang.c          | 55 ++++++++++++++++++++++++++++++++--
 lib/src/clixon_yang_internal.h |  1 +
 4 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f4775626..70c99c6f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,10 @@
 ## 6.6.0
 Expected: February 2024
 
+### Minor features
+
+* Added reference count for shared yang-specs (schema mounts)
+
 ## 6.5.0
 6 December 2023
 
diff --git a/lib/clixon/clixon_yang.h b/lib/clixon/clixon_yang.h
index 0eea5a33..5a0399c6 100644
--- a/lib/clixon/clixon_yang.h
+++ b/lib/clixon/clixon_yang.h
@@ -240,6 +240,9 @@ int        yang_cv_set(yang_stmt *ys, cg_var *cv);
 cvec      *yang_cvec_get(yang_stmt *ys);
 int        yang_cvec_set(yang_stmt *ys, cvec *cvv);
 cg_var    *yang_cvec_add(yang_stmt *ys, enum cv_type type, char *name);
+int        yang_ref_get(yang_stmt *ys);
+int        yang_ref_inc(yang_stmt *ys);
+int        yang_ref_dec(yang_stmt *ys);
 uint16_t   yang_flag_get(yang_stmt *ys, uint16_t flag);
 int        yang_flag_set(yang_stmt *ys, uint16_t flag);
 int        yang_flag_reset(yang_stmt *ys, uint16_t flag);
diff --git a/lib/src/clixon_yang.c b/lib/src/clixon_yang.c
index c167da2f..1d7971f1 100644
--- a/lib/src/clixon_yang.c
+++ b/lib/src/clixon_yang.c
@@ -345,6 +345,50 @@ yang_cvec_add(yang_stmt    *ys,
     return cv;
 }
 
+/*! Get yang object reference count
+ *
+ * @param[in]  ys    Yang statement
+ * @retval     ref   Reference coun t
+ */
+int 
+yang_ref_get(yang_stmt *ys)
+{
+    return ys->ys_ref;
+}
+
+/*! Increment yang object reference count with +1
+ *
+ * @param[in]  ys    Yang statement
+ * @retval     0
+ */
+int 
+yang_ref_inc(yang_stmt *ys)
+{
+    ys->ys_ref++;
+    return 0;
+}
+
+/*! Decrement yang object reference count with -1
+ *
+ * @param[in]  ys    Yang statement
+ * @retval     0     Ok
+ * @retval    -1     Error
+ */
+int 
+yang_ref_dec(yang_stmt *ys)
+{
+    int retval = -1;
+    
+    if (ys->ys_ref <= 0){
+        clicon_err(OE_YANG, 0, "reference count is %d cannot decrement", ys->ys_ref);
+        goto done;
+    }
+    ys->ys_ref--;
+    retval = 0;
+ done:
+    return retval;
+}
+
 /*! Get yang stmt flags, used for internal algorithms
  *
  * @param[in]  ys     Yang statement
@@ -813,12 +857,19 @@ ys_freechildren(yang_stmt *ys)
  * @param[in]  ys   Yang node to remove and all its children recursively
  * @note does not remove yang node from tree
  * @see ys_prune  Remove from parent
+ * @note special case of keeping track of reference counts if yang-spec
  */
 int
 ys_free(yang_stmt *ys)
 {
-    ys_freechildren(ys);
-    ys_free1(ys, 1);
+    if (yang_keyword_get(ys) == Y_SPEC &&
+        yang_ref_get(ys) > 0){
+        yang_ref_dec(ys);
+    }
+    else {
+        ys_freechildren(ys);
+        ys_free1(ys, 1);
+    }
     return 0;
 }
 
diff --git a/lib/src/clixon_yang_internal.h b/lib/src/clixon_yang_internal.h
index 8720f95d..3a2a59cc 100644
--- a/lib/src/clixon_yang_internal.h
+++ b/lib/src/clixon_yang_internal.h
@@ -101,6 +101,7 @@ struct yang_stmt{
                                         Y_EXTENSION: vector of instantiated UNKNOWNSo
                                         Y_UNKNOWN: app-dep: yang-mount-points
                                      */
+    int                ys_ref;       /* Reference count for free, only YS_SPEC */
     yang_type_cache   *ys_typecache; /* If ys_keyword==Y_TYPE, cache all typedef data except unions */
     char              *ys_when_xpath; /* Special conditional for a "when"-associated augment/uses xpath */
     cvec              *ys_when_nsc;   /* Special conditional for a "when"-associated augment/uses namespace ctx */