[Tarantool-patches] [PATCH 11/15] sql: introduce sql_stmt_sizeof() function

[Nikita Pettik <korablev@tarantool.org>]

To implement memory quota of prepared statement cache, we have to
estimate size of prepared statement. This function attempts at that.

Part of #2592
---
 src/box/execute.h     |  8 ++++++++
 src/box/sql/vdbeapi.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/src/box/execute.h b/src/box/execute.h
index 6702a18cc..d5b4d8421 100644
--- a/src/box/execute.h
+++ b/src/box/execute.h
@@ -116,6 +116,14 @@ extern const struct port_vtab port_sql_vtab;
 int
 sql_finalize(struct sql_stmt *stmt);
 
+/**
+ * Calculate estimated size of memory occupied by VM.
+ * See sqlVdbeMakeReady() for details concerning allocated
+ * memory.
+ */
+size_t
+sql_stmt_sizeof(const struct sql_stmt *stmt);
+
 /**
  * Prepare (compile into VDBE byte-code) statement.
  *
diff --git a/src/box/sql/vdbeapi.c b/src/box/sql/vdbeapi.c
index 23c4a250a..f5a7c1ab7 100644
--- a/src/box/sql/vdbeapi.c
+++ b/src/box/sql/vdbeapi.c
@@ -804,6 +804,55 @@ sql_schema_version(sql_stmt *stmt)
 	return ((struct Vdbe *)stmt)->schema_ver;
 }
 
+size_t
+sql_stmt_sizeof(const sql_stmt *stmt)
+{
+	struct Vdbe *v = (struct Vdbe *) stmt;
+	size_t size = sizeof(*v);
+	/* Resulting set */
+	size += sizeof(struct Mem) * v->nResColumn * COLNAME_N;
+	/* Opcodes */
+	size += sizeof(struct VdbeOp) * v->nOp;
+	/* Memory cells */
+	size += sizeof(struct Mem) * v->nMem;
+	/* Bindings */
+	size += sizeof(struct Mem) * v->nVar;
+	/* Bindings included in the result set */
+	size += sizeof(uint32_t) * v->res_var_count;
+	/* Cursors */
+	size += sizeof(struct VdbeCursor *) * v->nCursor;
+
+	for (int i = 0; i < v->nOp; ++i) {
+		/* Estimate size of p4 operand. */
+		if (v->aOp[i].p4type != P4_NOTUSED) {
+			switch (v->aOp[i].p4type) {
+				case P4_DYNAMIC:
+				case P4_STATIC:
+					size += strlen(v->aOp[i].p4.z);
+					break;
+				case P4_BOOL:
+					size += sizeof(v->aOp[i].p4.b);
+					break;
+				case P4_INT32:
+					size += sizeof(v->aOp[i].p4.i);
+					break;
+				case P4_UINT64:
+				case P4_INT64:
+					size += sizeof(*v->aOp[i].p4.pI64);
+					break;
+				case P4_REAL:
+					size += sizeof(*v->aOp[i].p4.pReal);
+					break;
+				default:
+					size += sizeof(v->aOp[i].p4.p);
+					break;
+			}
+		}
+	}
+	size += strlen(v->zSql);
+	return size;
+}
+
 /******************************* sql_bind_  **************************
  *
  * Routines used to attach values to wildcards in a compiled SQL statement.
-- 
2.15.1