From b1fd0ab73425e682a0a1404da6963f47a033bb34 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Wed, 30 Mar 2016 15:50:45 +0200
Subject: daemon: Improve the SQLite wrapper API.
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In particular, this eliminates a bunch of boilerplate code.

Also integrates these Nix commits:

  80da7a6 Probably fix SQLITE_BUSY errors
  37a337b throwSQLiteError(): Check for SIGINT so we don't loop forever

Co-authored-by: Ludovic Courtès <ludo@gnu.org>
---
 nix/libstore/sqlite.hh | 57 +++++++++++++++++++++++++++++++++-----------------
 1 file changed, 38 insertions(+), 19 deletions(-)

(limited to 'nix/libstore/sqlite.hh')

diff --git a/nix/libstore/sqlite.hh b/nix/libstore/sqlite.hh
index 0abdb74631..326e4a4855 100644
--- a/nix/libstore/sqlite.hh
+++ b/nix/libstore/sqlite.hh
@@ -22,29 +22,48 @@ struct SQLite
 /* RAII wrapper to create and destroy SQLite prepared statements. */
 struct SQLiteStmt
 {
-    sqlite3 * db;
-    sqlite3_stmt * stmt;
-    unsigned int curArg;
-    SQLiteStmt() { stmt = 0; }
+    sqlite3 * db = 0;
+    sqlite3_stmt * stmt = 0;
+    SQLiteStmt() { }
     void create(sqlite3 * db, const std::string & s);
-    void reset();
     ~SQLiteStmt();
     operator sqlite3_stmt * () { return stmt; }
-    void bind(const std::string & value);
-    void bind(int value);
-    void bind64(long long value);
-    void bind();
-};
 
-/* Helper class to ensure that prepared statements are reset when
-   leaving the scope that uses them.  Unfinished prepared statements
-   prevent transactions from being aborted, and can cause locks to be
-   kept when they should be released. */
-struct SQLiteStmtUse
-{
-    SQLiteStmt & stmt;
-    SQLiteStmtUse(SQLiteStmt & stmt);
-    ~SQLiteStmtUse();
+    /* Helper for binding / executing statements. */
+    class Use
+    {
+        friend struct SQLiteStmt;
+    private:
+        SQLiteStmt & stmt;
+        unsigned int curArg = 1;
+        Use(SQLiteStmt & stmt);
+
+    public:
+
+        ~Use();
+
+        /* Bind the next parameter. */
+        Use & operator () (const std::string & value, bool notNull = true);
+        Use & operator () (int64_t value, bool notNull = true);
+        Use & bind(); // null
+
+        int step();
+
+        /* Execute a statement that does not return rows. */
+        void exec();
+
+        /* For statements that return 0 or more rows. Returns true iff
+           a row is available. */
+        bool next();
+
+        std::string getStr(int col);
+        int64_t getInt(int col);
+    };
+
+    Use use()
+    {
+        return Use(*this);
+    }
 };
 
 /* RAII helper that ensures transactions are aborted unless explicitly
-- 
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