GitHub migration

1 files changed, 209 insertions, 0 deletions

diff --git a/updater/sql/mac/src/backup.h b/updater/sql/mac/src/backup.h
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+#ifndef NODE_SQLITE3_SRC_BACKUP_H
+#define NODE_SQLITE3_SRC_BACKUP_H
+
+#include "database.h"
+
+#include <string>
+#include <queue>
+#include <set>
+
+#include <sqlite3.h>
+#include <napi.h>
+
+using namespace Napi;
+
+namespace node_sqlite3 {
+
+/**
+ *
+ * A class for managing an sqlite3_backup object.  For consistency
+ * with other node-sqlite3 classes, it maintains an internal queue
+ * of calls.
+ *
+ * Intended usage from node:
+ *
+ *   var db = new sqlite3.Database('live.db');
+ *   var backup = db.backup('backup.db');
+ *   ...
+ *   // in event loop, move backup forward when we have time.
+ *   if (backup.idle) { backup.step(NPAGES); }
+ *   if (backup.completed) { ... success ... }
+ *   if (backup.failed)    { ... sadness ... }
+ *   // do other work in event loop - fine to modify live.db
+ *   ...
+ *
+ * Here is how sqlite's backup api is exposed:
+ *
+ *   - `sqlite3_backup_init`: This is implemented as
+ *     `db.backup(filename, [callback])` or
+ *     `db.backup(filename, destDbName, sourceDbName, filenameIsDest, [callback])`.
+ *   - `sqlite3_backup_step`: `backup.step(pages, [callback])`.
+ *   - `sqlite3_backup_finish`: `backup.finish([callback])`.
+ *   - `sqlite3_backup_remaining`: `backup.remaining`.
+ *   - `sqlite3_backup_pagecount`: `backup.pageCount`.
+ *
+ * There are the following read-only properties:
+ *
+ *   - `backup.completed` is set to `true` when the backup
+ *     succeeeds.
+ *   - `backup.failed` is set to `true` when the backup
+ *     has a fatal error.
+ *   - `backup.idle` is set to `true` when no operation
+ *     is currently in progress or queued for the backup.
+ *   - `backup.remaining` is an integer with the remaining
+ *     number of pages after the last call to `backup.step`
+ *     (-1 if `step` not yet called).
+ *   - `backup.pageCount` is an integer with the total number
+ *     of pages measured during the last call to `backup.step`
+ *     (-1 if `step` not yet called).
+ *
+ * There is the following writable property:
+ *
+ *   - `backup.retryErrors`: an array of sqlite3 error codes
+ *     that are treated as non-fatal - meaning, if they occur,
+ *     backup.failed is not set, and the backup may continue.
+ *     By default, this is `[sqlite3.BUSY, sqlite3.LOCKED]`.
+ *
+ * The `db.backup(filename, [callback])` shorthand is sufficient
+ * for making a backup of a database opened by node-sqlite3.  If
+ * using attached or temporary databases, or moving data in the
+ * opposite direction, the more complete (but daunting)
+ * `db.backup(filename, destDbName, sourceDbName, filenameIsDest, [callback])`
+ * signature is provided.
+ *
+ * A backup will finish automatically when it succeeds or a fatal
+ * error occurs, meaning it is not necessary to call `db.finish()`.
+ * By default, SQLITE_LOCKED and SQLITE_BUSY errors are not
+ * treated as failures, and the backup will continue if they
+ * occur.  The set of errors that are tolerated can be controlled
+ * by setting `backup.retryErrors`. To disable automatic
+ * finishing and stick strictly to sqlite's raw api, set
+ * `backup.retryErrors` to `[]`.  In that case, it is necessary
+ * to call `backup.finish()`.
+ *
+ * In the same way as node-sqlite3 databases and statements,
+ * backup methods can be called safely without callbacks, due
+ * to an internal call queue.  So for example this naive code
+ * will correctly back up a db, if there are no errors:
+ *
+ *   var backup = db.backup('backup.db');
+ *   backup.step(-1);
+ *   backup.finish();
+ *
+ */
+class Backup : public Napi::ObjectWrap<Backup> {
+public:
+    static Napi::Object Init(Napi::Env env, Napi::Object exports);
+
+    struct Baton {
+        napi_async_work request = NULL;
+        Backup* backup;
+        Napi::FunctionReference callback;
+
+        Baton(Backup* backup_, Napi::Function cb_) : backup(backup_) {
+            backup->Ref();
+            callback.Reset(cb_, 1);
+        }
+        virtual ~Baton() {
+            if (request) napi_delete_async_work(backup->Env(), request);
+            backup->Unref();
+            callback.Reset();
+        }
+    };
+
+    struct InitializeBaton : Database::Baton {
+        Backup* backup;
+        std::string filename;
+        std::string sourceName;
+        std::string destName;
+        bool filenameIsDest;
+        InitializeBaton(Database* db_, Napi::Function cb_, Backup* backup_) :
+            Baton(db_, cb_), backup(backup_), filenameIsDest(true) {
+            backup->Ref();
+        }
+        virtual ~InitializeBaton() override {
+            backup->Unref();
+            if (!db->IsOpen() && db->IsLocked()) {
+                // The database handle was closed before the backup could be opened.
+                backup->FinishAll();
+            }
+        }
+    };
+
+    struct StepBaton : Baton {
+        int pages;
+        std::set<int> retryErrorsSet;
+        StepBaton(Backup* backup_, Napi::Function cb_, int pages_) :
+            Baton(backup_, cb_), pages(pages_) {}
+        virtual ~StepBaton() override = default;
+    };
+
+    typedef void (*Work_Callback)(Baton* baton);
+
+    struct Call {
+        Call(Work_Callback cb_, Baton* baton_) : callback(cb_), baton(baton_) {};
+        Work_Callback callback;
+        Baton* baton;
+    };
+
+    Backup(const Napi::CallbackInfo& info);
+
+    ~Backup() {
+        if (!finished) {
+            FinishAll();
+        }
+        retryErrors.Reset();
+    }
+
+    WORK_DEFINITION(Step)
+    WORK_DEFINITION(Finish)
+
+    Napi::Value IdleGetter(const Napi::CallbackInfo& info);
+    Napi::Value CompletedGetter(const Napi::CallbackInfo& info);
+    Napi::Value FailedGetter(const Napi::CallbackInfo& info);
+    Napi::Value PageCountGetter(const Napi::CallbackInfo& info);
+    Napi::Value RemainingGetter(const Napi::CallbackInfo& info);
+    Napi::Value FatalErrorGetter(const Napi::CallbackInfo& info);
+    Napi::Value RetryErrorGetter(const Napi::CallbackInfo& info);
+
+    void FatalErrorSetter(const Napi::CallbackInfo& info, const Napi::Value& value);
+    void RetryErrorSetter(const Napi::CallbackInfo& info, const Napi::Value& value);
+
+protected:
+    static void Work_BeginInitialize(Database::Baton* baton);
+    static void Work_Initialize(napi_env env, void* data);
+    static void Work_AfterInitialize(napi_env env, napi_status status, void* data);
+
+    void Schedule(Work_Callback callback, Baton* baton);
+    void Process();
+    void CleanQueue();
+    template <class T> static void Error(T* baton);
+
+    void FinishAll();
+    void FinishSqlite();
+    void GetRetryErrors(std::set<int>& retryErrorsSet);
+
+    Database* db;
+
+    sqlite3_backup* _handle = NULL;
+    sqlite3* _otherDb = NULL;
+    sqlite3* _destDb = NULL;
+
+    bool inited = false;
+    bool locked = true;
+    bool completed = false;
+    bool failed = false;
+    int remaining = -1;
+    int pageCount = -1;
+    bool finished = false;
+
+    int status;
+    std::string message;
+    std::queue<std::unique_ptr<Call>> queue;
+
+    Napi::Reference<Array> retryErrors;
+};
+
+}
+
+#endif