daemon: Factor out SQLite handling.

* nix/libstore/local-store.cc: Move SQLite code to...
* nix/libstore/sqlite.cc, nix/libstore/sqlite.hh: ... here.  New files.
* nix/local.mk (libstore_a_SOURCES): Add sqlite.cc.
(libstore_headers): Add sqlite.hh.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 139 insertions, 0 deletions

diff --git a/nix/libstore/sqlite.cc b/nix/libstore/sqlite.cc
new file mode 100644
index 0000000000..8646ff5b12
--- /dev/null
+++ b/nix/libstore/sqlite.cc
@@ -0,0 +1,139 @@
+#include "sqlite.hh"
+#include "util.hh"
+
+#include <sqlite3.h>
+
+namespace nix {
+
+[[noreturn]] void throwSQLiteError(sqlite3 * db, const format & f)
+{
+    int err = sqlite3_errcode(db);
+    if (err == SQLITE_BUSY || err == SQLITE_PROTOCOL) {
+        if (err == SQLITE_PROTOCOL)
+            printMsg(lvlError, "warning: SQLite database is busy (SQLITE_PROTOCOL)");
+        else {
+            static bool warned = false;
+            if (!warned) {
+                printMsg(lvlError, "warning: SQLite database is busy");
+                warned = true;
+            }
+        }
+        /* Sleep for a while since retrying the transaction right away
+           is likely to fail again. */
+#if HAVE_NANOSLEEP
+        struct timespec t;
+        t.tv_sec = 0;
+        t.tv_nsec = (random() % 100) * 1000 * 1000; /* <= 0.1s */
+        nanosleep(&t, 0);
+#else
+        sleep(1);
+#endif
+        throw SQLiteBusy(format("%1%: %2%") % f.str() % sqlite3_errmsg(db));
+    }
+    else
+        throw SQLiteError(format("%1%: %2%") % f.str() % sqlite3_errmsg(db));
+}
+
+SQLite::~SQLite()
+{
+    try {
+        if (db && sqlite3_close(db) != SQLITE_OK)
+            throwSQLiteError(db, "closing database");
+    } catch (...) {
+        ignoreException();
+    }
+}
+
+void SQLiteStmt::create(sqlite3 * db, const string & s)
+{
+    checkInterrupt();
+    assert(!stmt);
+    if (sqlite3_prepare_v2(db, s.c_str(), -1, &stmt, 0) != SQLITE_OK)
+        throwSQLiteError(db, "creating statement");
+    this->db = db;
+}
+
+void SQLiteStmt::reset()
+{
+    assert(stmt);
+    /* Note: sqlite3_reset() returns the error code for the most
+       recent call to sqlite3_step().  So ignore it. */
+    sqlite3_reset(stmt);
+    curArg = 1;
+}
+
+SQLiteStmt::~SQLiteStmt()
+{
+    try {
+        if (stmt && sqlite3_finalize(stmt) != SQLITE_OK)
+            throwSQLiteError(db, "finalizing statement");
+    } catch (...) {
+        ignoreException();
+    }
+}
+
+void SQLiteStmt::bind(const string & value)
+{
+    if (sqlite3_bind_text(stmt, curArg++, value.c_str(), -1, SQLITE_TRANSIENT) != SQLITE_OK)
+        throwSQLiteError(db, "binding argument");
+}
+
+void SQLiteStmt::bind(int value)
+{
+    if (sqlite3_bind_int(stmt, curArg++, value) != SQLITE_OK)
+        throwSQLiteError(db, "binding argument");
+}
+
+void SQLiteStmt::bind64(long long value)
+{
+    if (sqlite3_bind_int64(stmt, curArg++, value) != SQLITE_OK)
+        throwSQLiteError(db, "binding argument");
+}
+
+void SQLiteStmt::bind()
+{
+    if (sqlite3_bind_null(stmt, curArg++) != SQLITE_OK)
+        throwSQLiteError(db, "binding argument");
+}
+
+SQLiteStmtUse::SQLiteStmtUse(SQLiteStmt & stmt)
+    : stmt(stmt)
+{
+    stmt.reset();
+}
+
+SQLiteStmtUse::~SQLiteStmtUse()
+{
+    try {
+        stmt.reset();
+    } catch (...) {
+        ignoreException();
+    }
+}
+
+SQLiteTxn::SQLiteTxn(sqlite3 * db)
+{
+    this->db = db;
+    if (sqlite3_exec(db, "begin;", 0, 0, 0) != SQLITE_OK)
+        throwSQLiteError(db, "starting transaction");
+    active = true;
+}
+
+void SQLiteTxn::commit()
+{
+    if (sqlite3_exec(db, "commit;", 0, 0, 0) != SQLITE_OK)
+        throwSQLiteError(db, "committing transaction");
+    active = false;
+}
+
+SQLiteTxn::~SQLiteTxn()
+{
+    try {
+        if (active && sqlite3_exec(db, "rollback;", 0, 0, 0) != SQLITE_OK)
+            throwSQLiteError(db, "aborting transaction");
+    } catch (...) {
+        ignoreException();
+    }
+}
+
+}