[Tarantool-patches] [PATCH v3 13/20] sql: introduce sql_stmt_sizeof() function

[Nikita Pettik]

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 | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/src/box/execute.h b/src/box/execute.h
index c87e765cf..2dd4fca03 100644
--- a/src/box/execute.h
+++ b/src/box/execute.h
@@ -113,6 +113,14 @@ extern const struct port_vtab port_sql_vtab;
 int
 sql_stmt_finalize(struct sql_stmt *stmt);
 
+/**
+ * Calculate estimated size of memory occupied by VM.
+ * See sqlVdbeMakeReady() for details concerning allocated
+ * memory.
+ */
+size_t
+sql_stmt_est_size(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 7d9ce11e7..2ac174112 100644
--- a/src/box/sql/vdbeapi.c
+++ b/src/box/sql/vdbeapi.c
@@ -805,6 +805,59 @@ sql_stmt_schema_version(const struct sql_stmt *stmt)
 	return v->schema_ver;
 }
 
+size_t
+sql_stmt_est_size(const struct sql_stmt *stmt)
+{
+	struct Vdbe *v = (struct Vdbe *) stmt;
+	size_t size = sizeof(*v);
+	/* Names and types of result set columns */
+	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)
+			continue;
+		switch (v->aOp[i].p4type) {
+		case P4_DYNAMIC:
+		case P4_STATIC:
+			if (v->aOp[i].opcode == OP_Blob ||
+			    v->aOp[i].opcode == OP_String)
+				size += v->aOp[i].p1;
+			else if (v->aOp[i].opcode == OP_String8)
+				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