1.1--- a/lisp/ffi/rocksdb/merge.lisp	Thu Aug 15 21:54:36 2024 -0400
     1.2+++ b/lisp/ffi/rocksdb/merge.lisp	Thu Aug 15 23:36:34 2024 -0400
     1.3@@ -34,6 +34,16 @@
     1.4 ;;; Code:
     1.5 (in-package :rocksdb)
     1.6 
     1.7+#|
     1.8+Gives the client a way to express the read -> modify -> write semantics
     1.9+key:         (IN) The key that's associated with this merge operation.
    1.10+existing:    (IN) null indicates that the key does not exist before this op
    1.11+operand_list:(IN) the sequence of merge operations to apply, front() first.
    1.12+new_value:  (OUT) Client is responsible for filling the merge result here
    1.13+logger:      (IN) Client could use this to log errors during merge.
    1.14+
    1.15+Return true on success. Return false failure / error / corruption.
    1.16+|#
    1.17 ;; FullMerge() is used when a Put/Delete is the *existing_value (or null)
    1.18 (define-alien-type rocksdb-full-merge-function
    1.19     (function (* t)
    1.20@@ -44,6 +54,13 @@
    1.21               int
    1.22               (array unsigned-char)
    1.23               (* size-t)))
    1.24+
    1.25+#|
    1.26+This function performs merge(left_op, right_op)
    1.27+when both the operands are themselves merge operation types.
    1.28+Save the result in *new_value and return true. If it is impossible
    1.29+or infeasible to combine the two operations, return false instead.
    1.30+|#
    1.31 ;; PartialMerge() is used to combine two-merge operands (if possible)
    1.32 (define-alien-type rocksdb-partial-merge-function
    1.33     (function (* t)
    1.34@@ -63,6 +80,11 @@
    1.35 (define-alien-type rocksdb-destructor-function
    1.36   (function void (* t)))
    1.37 
    1.38+#|
    1.39+The name of the MergeOperator. Used to check for MergeOperator
    1.40+mismatches (i.e., a DB created with one MergeOperator is
    1.41+accessed using a different MergeOperator)
    1.42+|#
    1.43 (define-alien-type rocksdb-name-function
    1.44     (function c-string))
    1.45 
    1.46@@ -76,7 +98,7 @@
    1.47   (full-merge (* rocksdb-full-merge-function))
    1.48   (partial-merge (* rocksdb-partial-merge-function))
    1.49   (delete-value (* rocksdb-delete-value-function))
    1.50-  (name c-string))
    1.51+  (name (* rocksdb-name-function)))
    1.52 
    1.53 #| [[file:~/dev/comp/core/c/rocksdb.h::/* Merge Operator */]] |#
    1.54 
    1.55@@ -101,7 +123,7 @@
    1.56 
    1.57 (define-alien-callable rocksdb-name c-string () (make-alien-string (symbol-name (gensym "rocksdb:"))))
    1.58 
    1.59-(define-alien-callable rocksdb-concat-full-merge (* t)
    1.60+(define-alien-callable rocksdb-concat-full-merge boolean
    1.61     ((key (array unsigned-char))
    1.62      (klen size-t)
    1.63      (existing-val (array unsigned-char))
    1.64@@ -112,9 +134,9 @@
    1.65      (success (array unsigned-char))
    1.66      (new-vlen (* size-t)))
    1.67   (log:debug! (list key klen existing-val existing-vlen ops ops-length num-ops success new-vlen))
    1.68-  nil)
    1.69+  1)
    1.70 
    1.71-(define-alien-callable rocksdb-concat-partial-merge (* t)
    1.72+(define-alien-callable rocksdb-concat-partial-merge boolean
    1.73     ((key (array unsigned-char))
    1.74      (klen size-t)
    1.75      (ops (array (array unsigned-char)))
    1.76@@ -123,4 +145,4 @@
    1.77      (success (array unsigned-char))
    1.78      (new-vlen (* size-t)))
    1.79   (log:debug! (list key klen ops ops-length num-ops success new-vlen))
    1.80-  nil)
    1.81+  0)