GitHub migration

1 files changed, 939 insertions, 0 deletions

diff --git a/updater/sql/win/src/statement.cc b/updater/sql/win/src/statement.cc
new file mode 100755
index 0000000..fc49b90
--- /dev/null
+++ b/updater/sql/win/src/statement.cc
@@ -0,0 +1,939 @@
+#include <cstring>
+#include <napi.h>
+#include <uv.h>
+
+#include "macros.h"
+#include "database.h"
+#include "statement.h"
+
+using namespace node_sqlite3;
+
+Napi::Object Statement::Init(Napi::Env env, Napi::Object exports) {
+    Napi::HandleScope scope(env);
+
+    // declare napi_default_method here as it is only available in Node v14.12.0+
+    auto napi_default_method = static_cast<napi_property_attributes>(napi_writable | napi_configurable);
+
+    auto t = DefineClass(env, "Statement", {
+      InstanceMethod("bind", &Statement::Bind, napi_default_method),
+      InstanceMethod("get", &Statement::Get, napi_default_method),
+      InstanceMethod("run", &Statement::Run, napi_default_method),
+      InstanceMethod("all", &Statement::All, napi_default_method),
+      InstanceMethod("each", &Statement::Each, napi_default_method),
+      InstanceMethod("reset", &Statement::Reset, napi_default_method),
+      InstanceMethod("finalize", &Statement::Finalize_, napi_default_method),
+    });
+
+    exports.Set("Statement", t);
+    return exports;
+}
+
+// A Napi InstanceOf for Javascript Objects "Date" and "RegExp"
+bool OtherInstanceOf(Napi::Object source, const char* object_type) {
+    if (strncmp(object_type, "Date", 4) == 0) {
+        return source.InstanceOf(source.Env().Global().Get("Date").As<Function>());
+    } else if (strncmp(object_type, "RegExp", 6) == 0) {
+        return source.InstanceOf(source.Env().Global().Get("RegExp").As<Function>());
+    }
+
+    return false;
+}
+
+void Statement::Process() {
+    if (finalized && !queue.empty()) {
+        return CleanQueue();
+    }
+
+    while (prepared && !locked && !queue.empty()) {
+        auto call = std::unique_ptr<Call>(queue.front());
+        queue.pop();
+
+        call->callback(call->baton);
+    }
+}
+
+void Statement::Schedule(Work_Callback callback, Baton* baton) {
+    if (finalized) {
+        queue.emplace(new Call(callback, baton));
+        CleanQueue();
+    }
+    else if (!prepared || locked) {
+        queue.emplace(new Call(callback, baton));
+    }
+    else {
+        callback(baton);
+    }
+}
+
+template <class T> void Statement::Error(T* baton) {
+    Statement* stmt = baton->stmt;
+
+    auto env = stmt->Env();
+    Napi::HandleScope scope(env);
+
+    // Fail hard on logic errors.
+    assert(stmt->status != 0);
+    EXCEPTION(Napi::String::New(env, stmt->message.c_str()), stmt->status, exception);
+
+    Napi::Function cb = baton->callback.Value();
+
+    if (IS_FUNCTION(cb)) {
+        Napi::Value argv[] = { exception };
+        TRY_CATCH_CALL(stmt->Value(), cb, 1, argv);
+    }
+    else {
+        Napi::Value argv[] = { Napi::String::New(env, "error"), exception };
+        EMIT_EVENT(stmt->Value(), 2, argv);
+    }
+}
+
+// { Database db, String sql, Array params, Function callback }
+Statement::Statement(const Napi::CallbackInfo& info) : Napi::ObjectWrap<Statement>(info) {
+    auto env = info.Env();
+    int length = info.Length();
+
+    if (length <= 0 || !Database::HasInstance(info[0])) {
+        Napi::TypeError::New(env, "Database object expected").ThrowAsJavaScriptException();
+        return;
+    }
+    else if (length <= 1 || !info[1].IsString()) {
+        Napi::TypeError::New(env, "SQL query expected").ThrowAsJavaScriptException();
+        return;
+    }
+    else if (length > 2 && !info[2].IsUndefined() && !info[2].IsFunction()) {
+        Napi::TypeError::New(env, "Callback expected").ThrowAsJavaScriptException();
+        return;
+    }
+
+    this->db = Napi::ObjectWrap<Database>::Unwrap(info[0].As<Napi::Object>());
+    this->db->Ref();
+
+    auto sql = info[1].As<Napi::String>();
+
+    info.This().As<Napi::Object>().DefineProperty(Napi::PropertyDescriptor::Value("sql", sql, napi_default));
+
+
+    Statement* stmt = this;
+
+    auto* baton = new PrepareBaton(this->db, info[2].As<Napi::Function>(), stmt);
+    baton->sql = std::string(sql.As<Napi::String>().Utf8Value().c_str());
+    this->db->Schedule(Work_BeginPrepare, baton);
+}
+
+void Statement::Work_BeginPrepare(Database::Baton* baton) {
+    assert(baton->db->open);
+    baton->db->pending++;
+
+    auto env = baton->db->Env();
+    CREATE_WORK("sqlite3.Statement.Prepare", Work_Prepare, Work_AfterPrepare);
+}
+
+void Statement::Work_Prepare(napi_env e, void* data) {
+    STATEMENT_INIT(PrepareBaton);
+
+    // In case preparing fails, we use a mutex to make sure we get the associated
+    // error message.
+    STATEMENT_MUTEX(mtx);
+    sqlite3_mutex_enter(mtx);
+
+    stmt->status = sqlite3_prepare_v2(
+        baton->db->_handle,
+        baton->sql.c_str(),
+        baton->sql.size(),
+        &stmt->_handle,
+        NULL
+    );
+
+    if (stmt->status != SQLITE_OK) {
+        stmt->message = std::string(sqlite3_errmsg(baton->db->_handle));
+        stmt->_handle = NULL;
+    }
+
+    sqlite3_mutex_leave(mtx);
+}
+
+void Statement::Work_AfterPrepare(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<PrepareBaton> baton(static_cast<PrepareBaton*>(data));
+    auto* stmt = baton->stmt;
+
+    auto env = stmt->Env();
+    Napi::HandleScope scope(env);
+
+    if (stmt->status != SQLITE_OK) {
+        Error(baton.get());
+        stmt->Finalize_();
+    }
+    else {
+        stmt->prepared = true;
+        if (!baton->callback.IsEmpty() && baton->callback.Value().IsFunction()) {
+            Napi::Function cb = baton->callback.Value();
+            Napi::Value argv[] = { env.Null() };
+            TRY_CATCH_CALL(stmt->Value(), cb, 1, argv);
+        }
+    }
+
+    STATEMENT_END();
+}
+
+template <class T> std::unique_ptr<Values::Field>
+                   Statement::BindParameter(const Napi::Value source, T pos) {
+    if (source.IsString()) {
+        std::string val = source.As<Napi::String>().Utf8Value();
+        return std::make_unique<Values::Text>(pos, val.length(), val.c_str());
+    }
+    else if (OtherInstanceOf(source.As<Object>(), "RegExp")) {
+        std::string val = source.ToString().Utf8Value();
+        return std::make_unique<Values::Text>(pos, val.length(), val.c_str());
+    }
+    else if (source.IsNumber()) {
+        if (OtherIsInt(source.As<Napi::Number>())) {
+            return std::make_unique<Values::Integer>(pos, source.As<Napi::Number>().Int32Value());
+        } else {
+            return std::make_unique<Values::Float>(pos, source.As<Napi::Number>().DoubleValue());
+        }
+    }
+    else if (source.IsBoolean()) {
+        return std::make_unique<Values::Integer>(pos, source.As<Napi::Boolean>().Value() ? 1 : 0);
+    }
+    else if (source.IsNull()) {
+        return std::make_unique<Values::Null>(pos);
+    }
+    else if (source.IsBuffer()) {
+        Napi::Buffer<char> buffer = source.As<Napi::Buffer<char>>();
+        return std::make_unique<Values::Blob>(pos, buffer.Length(), buffer.Data());
+    }
+    else if (OtherInstanceOf(source.As<Object>(), "Date")) {
+        return std::make_unique<Values::Float>(pos, source.ToNumber().DoubleValue());
+    }
+    else if (source.IsObject()) {
+        auto napiVal = Napi::String::New(source.Env(), "[object Object]");
+        // Check whether toString returned a value that is not undefined.
+        if(napiVal.Type() == 0) {
+            return NULL;
+        }
+
+        std::string val = napiVal.Utf8Value();
+        return std::make_unique<Values::Text>(pos, val.length(), val.c_str());
+    }
+    else {
+        return NULL;
+    }
+}
+
+template <class T> T* Statement::Bind(const Napi::CallbackInfo& info, int start, int last) {
+    auto env = info.Env();
+    Napi::HandleScope scope(env);
+
+    if (last < 0) last = info.Length();
+    Napi::Function callback;
+    if (last > start && info[last - 1].IsFunction()) {
+        callback = info[last - 1].As<Napi::Function>();
+        last--;
+    }
+
+    auto *baton = new T(this, callback);
+
+    if (start < last) {
+        if (info[start].IsArray()) {
+            auto array = info[start].As<Napi::Array>();
+            int length = array.Length();
+            // Note: bind parameters start with 1.
+            for (int i = 0, pos = 1; i < length; i++, pos++) {
+                baton->parameters.emplace_back(BindParameter((array).Get(i), i + 1));
+            }
+        }
+        else if (!info[start].IsObject() || OtherInstanceOf(info[start].As<Object>(), "RegExp") 
+                || OtherInstanceOf(info[start].As<Object>(), "Date") || info[start].IsBuffer()) {
+            // Parameters directly in array.
+            // Note: bind parameters start with 1.
+            for (int i = start, pos = 1; i < last; i++, pos++) {
+                baton->parameters.emplace_back(BindParameter(info[i], pos));
+            }
+        }
+        else if (info[start].IsObject()) {
+            auto object = info[start].As<Napi::Object>();
+            auto array = object.GetPropertyNames();
+            int length = array.Length();
+            for (int i = 0; i < length; i++) {
+                Napi::Value name = (array).Get(i);
+                Napi::Number num = name.ToNumber();
+
+                if (num.Int32Value() == num.DoubleValue()) {
+                    baton->parameters.emplace_back(
+                        BindParameter((object).Get(name), num.Int32Value()));
+                }
+                else {
+                    baton->parameters.emplace_back(BindParameter((object).Get(name),
+                        name.As<Napi::String>().Utf8Value().c_str()));
+                }
+            }
+        }
+        else {
+            return NULL;
+        }
+    }
+
+    return baton;
+}
+
+bool Statement::Bind(const Parameters & parameters) {
+    if (parameters.empty()) {
+        return true;
+    }
+
+    sqlite3_reset(_handle);
+    sqlite3_clear_bindings(_handle);
+
+    for (auto& field : parameters) {
+        if (field == NULL)
+            continue;
+
+        unsigned int pos;
+        if (field->index > 0) {
+            pos = field->index;
+        }
+        else {
+            pos = sqlite3_bind_parameter_index(_handle, field->name.c_str());
+        }
+
+        switch (field->type) {
+            case SQLITE_INTEGER: {
+                status = sqlite3_bind_int(_handle, pos,
+                    (static_cast<Values::Integer*>(field.get()))->value);
+            } break;
+            case SQLITE_FLOAT: {
+                status = sqlite3_bind_double(_handle, pos,
+                    (static_cast<Values::Float*>(field.get()))->value);
+            } break;
+            case SQLITE_TEXT: {
+                status = sqlite3_bind_text(_handle, pos,
+                    (static_cast<Values::Text*>(field.get()))->value.c_str(),
+                    (static_cast<Values::Text*>(field.get()))->value.size(), SQLITE_TRANSIENT);
+            } break;
+            case SQLITE_BLOB: {
+                status = sqlite3_bind_blob(_handle, pos,
+                    (static_cast<Values::Blob*>(field.get()))->value,
+                    (static_cast<Values::Blob*>(field.get()))->length, SQLITE_TRANSIENT);
+            } break;
+            case SQLITE_NULL: {
+                status = sqlite3_bind_null(_handle, pos);
+            } break;
+        }
+
+            if (status != SQLITE_OK) {
+                message = std::string(sqlite3_errmsg(db->_handle));
+                return false;
+            }
+        }
+
+    return true;
+}
+
+Napi::Value Statement::Bind(const Napi::CallbackInfo& info) {
+    auto env = info.Env();
+    Statement* stmt = this;
+
+    auto baton = stmt->Bind<Baton>(info);
+    if (baton == NULL) {
+        Napi::TypeError::New(env, "Data type is not supported").ThrowAsJavaScriptException();
+        return env.Null();
+    }
+    else {
+        stmt->Schedule(Work_BeginBind, baton);
+        return info.This();
+    }
+}
+
+void Statement::Work_BeginBind(Baton* baton) {
+    STATEMENT_BEGIN(Bind);
+}
+
+void Statement::Work_Bind(napi_env e, void* data) {
+    STATEMENT_INIT(Baton);
+
+    STATEMENT_MUTEX(mtx);
+    sqlite3_mutex_enter(mtx);
+    stmt->Bind(baton->parameters);
+    sqlite3_mutex_leave(mtx);
+}
+
+void Statement::Work_AfterBind(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<Baton> baton(static_cast<Baton*>(data));
+    auto* stmt = baton->stmt;
+
+    auto env = stmt->Env();
+    Napi::HandleScope scope(env);
+
+    if (stmt->status != SQLITE_OK) {
+        Error(baton.get());
+    }
+    else {
+        // Fire callbacks.
+        Napi::Function cb = baton->callback.Value();
+        if (IS_FUNCTION(cb)) {
+            Napi::Value argv[] = { env.Null() };
+            TRY_CATCH_CALL(stmt->Value(), cb, 1, argv);
+        }
+    }
+
+    STATEMENT_END();
+}
+
+
+
+Napi::Value Statement::Get(const Napi::CallbackInfo& info) {
+    auto env = info.Env();
+    Statement* stmt = this;
+
+    Baton* baton = stmt->Bind<RowBaton>(info);
+    if (baton == NULL) {
+        Napi::Error::New(env, "Data type is not supported").ThrowAsJavaScriptException();
+        return env.Null();
+    }
+    else {
+        stmt->Schedule(Work_BeginGet, baton);
+        return info.This();
+    }
+}
+
+void Statement::Work_BeginGet(Baton* baton) {
+    STATEMENT_BEGIN(Get);
+}
+
+void Statement::Work_Get(napi_env e, void* data) {
+    STATEMENT_INIT(RowBaton);
+
+    if (stmt->status != SQLITE_DONE || baton->parameters.size()) {
+        STATEMENT_MUTEX(mtx);
+        sqlite3_mutex_enter(mtx);
+
+        if (stmt->Bind(baton->parameters)) {
+            stmt->status = sqlite3_step(stmt->_handle);
+
+            if (!(stmt->status == SQLITE_ROW || stmt->status == SQLITE_DONE)) {
+                stmt->message = std::string(sqlite3_errmsg(stmt->db->_handle));
+            }
+        }
+
+        sqlite3_mutex_leave(mtx);
+
+        if (stmt->status == SQLITE_ROW) {
+            // Acquire one result row before returning.
+            GetRow(&baton->row, stmt->_handle);
+        }
+    }
+}
+
+void Statement::Work_AfterGet(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<RowBaton> baton(static_cast<RowBaton*>(data));
+    auto* stmt = baton->stmt;
+
+    auto env = stmt->Env();
+    Napi::HandleScope scope(env);
+
+    if (stmt->status != SQLITE_ROW && stmt->status != SQLITE_DONE) {
+        Error(baton.get());
+    }
+    else {
+        // Fire callbacks.
+        Napi::Function cb = baton->callback.Value();
+        if (IS_FUNCTION(cb)) {
+            if (stmt->status == SQLITE_ROW) {
+                // Create the result array from the data we acquired.
+                Napi::Value argv[] = { env.Null(), RowToJS(env, &baton->row) };
+                TRY_CATCH_CALL(stmt->Value(), cb, 2, argv);
+            }
+            else {
+                Napi::Value argv[] = { env.Null() };
+                TRY_CATCH_CALL(stmt->Value(), cb, 1, argv);
+            }
+        }
+    }
+
+    STATEMENT_END();
+}
+
+Napi::Value Statement::Run(const Napi::CallbackInfo& info) {
+    auto env = info.Env();
+    Statement* stmt = this;
+
+    Baton* baton = stmt->Bind<RunBaton>(info);
+    if (baton == NULL) {
+        Napi::Error::New(env, "Data type is not supported").ThrowAsJavaScriptException();
+        return env.Null();
+    }
+    else {
+        stmt->Schedule(Work_BeginRun, baton);
+        return info.This();
+    }
+}
+
+void Statement::Work_BeginRun(Baton* baton) {
+    STATEMENT_BEGIN(Run);
+}
+
+void Statement::Work_Run(napi_env e, void* data) {
+    STATEMENT_INIT(RunBaton);
+
+    STATEMENT_MUTEX(mtx);
+    sqlite3_mutex_enter(mtx);
+
+    // Make sure that we also reset when there are no parameters.
+    if (!baton->parameters.size()) {
+        sqlite3_reset(stmt->_handle);
+    }
+
+    if (stmt->Bind(baton->parameters)) {
+        stmt->status = sqlite3_step(stmt->_handle);
+
+        if (!(stmt->status == SQLITE_ROW || stmt->status == SQLITE_DONE)) {
+            stmt->message = std::string(sqlite3_errmsg(stmt->db->_handle));
+        }
+        else {
+            baton->inserted_id = sqlite3_last_insert_rowid(stmt->db->_handle);
+            baton->changes = sqlite3_changes(stmt->db->_handle);
+        }
+    }
+
+    sqlite3_mutex_leave(mtx);
+}
+
+void Statement::Work_AfterRun(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<RunBaton> baton(static_cast<RunBaton*>(data));
+    auto* stmt = baton->stmt;
+
+    auto env = stmt->Env();
+    Napi::HandleScope scope(env);
+
+    if (stmt->status != SQLITE_ROW && stmt->status != SQLITE_DONE) {
+        Error(baton.get());
+    }
+    else {
+        // Fire callbacks.
+        Napi::Function cb = baton->callback.Value();
+        if (IS_FUNCTION(cb)) {
+            (stmt->Value()).Set(Napi::String::New(env, "lastID"), Napi::Number::New(env, baton->inserted_id));
+            (stmt->Value()).Set( Napi::String::New(env, "changes"), Napi::Number::New(env, baton->changes));
+
+            Napi::Value argv[] = { env.Null() };
+            TRY_CATCH_CALL(stmt->Value(), cb, 1, argv);
+        }
+    }
+
+    STATEMENT_END();
+}
+
+Napi::Value Statement::All(const Napi::CallbackInfo& info) {
+    auto env = info.Env();
+    Statement* stmt = this;
+
+    Baton* baton = stmt->Bind<RowsBaton>(info);
+    if (baton == NULL) {
+        Napi::Error::New(env, "Data type is not supported").ThrowAsJavaScriptException();
+        return env.Null();
+    }
+    else {
+        stmt->Schedule(Work_BeginAll, baton);
+        return info.This();
+    }
+}
+
+void Statement::Work_BeginAll(Baton* baton) {
+    STATEMENT_BEGIN(All);
+}
+
+void Statement::Work_All(napi_env e, void* data) {
+    STATEMENT_INIT(RowsBaton);
+
+    STATEMENT_MUTEX(mtx);
+    sqlite3_mutex_enter(mtx);
+
+    // Make sure that we also reset when there are no parameters.
+    if (!baton->parameters.size()) {
+        sqlite3_reset(stmt->_handle);
+    }
+
+    if (stmt->Bind(baton->parameters)) {
+        while ((stmt->status = sqlite3_step(stmt->_handle)) == SQLITE_ROW) {
+            auto row = std::make_unique<Row>();
+            GetRow(row.get(), stmt->_handle);
+            baton->rows.emplace_back(std::move(row));
+        }
+
+        if (stmt->status != SQLITE_DONE) {
+            stmt->message = std::string(sqlite3_errmsg(stmt->db->_handle));
+        }
+    }
+
+    sqlite3_mutex_leave(mtx);
+}
+
+void Statement::Work_AfterAll(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<RowsBaton> baton(static_cast<RowsBaton*>(data));
+    auto* stmt = baton->stmt;
+
+    auto env = stmt->Env();
+    Napi::HandleScope scope(env);
+
+    if (stmt->status != SQLITE_DONE) {
+        Error(baton.get());
+    }
+    else {
+        // Fire callbacks.
+        Napi::Function cb = baton->callback.Value();
+        if (IS_FUNCTION(cb)) {
+            if (baton->rows.size()) {
+                // Create the result array from the data we acquired.
+                Napi::Array result(Napi::Array::New(env, baton->rows.size()));
+                auto it = static_cast<Rows::const_iterator>(baton->rows.begin());
+                decltype(it) end = baton->rows.end();
+                for (int i = 0; it < end; ++it, i++) {
+                    (result).Set(i, RowToJS(env, it->get()));
+                }
+
+                Napi::Value argv[] = { env.Null(), result };
+                TRY_CATCH_CALL(stmt->Value(), cb, 2, argv);
+            }
+            else {
+                // There were no result rows.
+                Napi::Value argv[] = {
+                    env.Null(),
+                    Napi::Array::New(env, 0)
+                };
+                TRY_CATCH_CALL(stmt->Value(), cb, 2, argv);
+            }
+        }
+    }
+
+    STATEMENT_END();
+}
+
+Napi::Value Statement::Each(const Napi::CallbackInfo& info) {
+    auto env = info.Env();
+    Statement* stmt = this;
+
+    int last = info.Length();
+
+    Napi::Function completed;
+    if (last >= 2 && info[last - 1].IsFunction() && info[last - 2].IsFunction()) {
+        completed = info[--last].As<Napi::Function>();
+    }
+
+    auto baton = stmt->Bind<EachBaton>(info, 0, last);
+    if (baton == NULL) {
+        Napi::Error::New(env, "Data type is not supported").ThrowAsJavaScriptException();
+        return env.Null();
+    }
+    else {
+        baton->completed.Reset(completed, 1);
+        stmt->Schedule(Work_BeginEach, baton);
+        return info.This();
+    }
+}
+
+void Statement::Work_BeginEach(Baton* baton) {
+    // Only create the Async object when we're actually going into
+    // the event loop. This prevents dangling events.
+    auto* each_baton = static_cast<EachBaton*>(baton);
+    each_baton->async = new Async(each_baton->stmt, reinterpret_cast<uv_async_cb>(AsyncEach));
+    each_baton->async->item_cb.Reset(each_baton->callback.Value(), 1);
+    each_baton->async->completed_cb.Reset(each_baton->completed.Value(), 1);
+
+    STATEMENT_BEGIN(Each);
+}
+
+void Statement::Work_Each(napi_env e, void* data) {
+    STATEMENT_INIT(EachBaton);
+
+    auto* async = baton->async;
+
+    STATEMENT_MUTEX(mtx);
+
+    // Make sure that we also reset when there are no parameters.
+    if (!baton->parameters.size()) {
+        sqlite3_reset(stmt->_handle);
+    }
+
+    if (stmt->Bind(baton->parameters)) {
+        while (true) {
+            sqlite3_mutex_enter(mtx);
+            stmt->status = sqlite3_step(stmt->_handle);
+            if (stmt->status == SQLITE_ROW) {
+                sqlite3_mutex_leave(mtx);
+                auto row = std::make_unique<Row>();
+                GetRow(row.get(), stmt->_handle);
+                NODE_SQLITE3_MUTEX_LOCK(&async->mutex)
+                async->data.emplace_back(std::move(row));
+                NODE_SQLITE3_MUTEX_UNLOCK(&async->mutex)
+
+                uv_async_send(&async->watcher);
+            }
+            else {
+                if (stmt->status != SQLITE_DONE) {
+                    stmt->message = std::string(sqlite3_errmsg(stmt->db->_handle));
+                }
+                sqlite3_mutex_leave(mtx);
+                break;
+            }
+        }
+    }
+
+    async->completed = true;
+    uv_async_send(&async->watcher);
+}
+
+void Statement::CloseCallback(uv_handle_t* handle) {
+    assert(handle != NULL);
+    assert(handle->data != NULL);
+    auto* async = static_cast<Async*>(handle->data);
+    delete async;
+}
+
+void Statement::AsyncEach(uv_async_t* handle) {
+    auto* async = static_cast<Async*>(handle->data);
+
+    auto env = async->stmt->Env();
+    Napi::HandleScope scope(env);
+
+    while (true) {
+        // Get the contents out of the data cache for us to process in the JS callback.
+        Rows rows;
+        NODE_SQLITE3_MUTEX_LOCK(&async->mutex)
+        rows.swap(async->data);
+        NODE_SQLITE3_MUTEX_UNLOCK(&async->mutex)
+
+        if (rows.empty()) {
+            break;
+        }
+
+        Napi::Function cb = async->item_cb.Value();
+        if (IS_FUNCTION(cb)) {
+            Napi::Value argv[2];
+            argv[0] = env.Null();
+
+            for(auto& row : rows) {
+                argv[1] = RowToJS(env,row.get());
+                async->retrieved++;
+                TRY_CATCH_CALL(async->stmt->Value(), cb, 2, argv);
+            }
+        }
+    }
+
+    Napi::Function cb = async->completed_cb.Value();
+    if (async->completed) {
+        if (!cb.IsEmpty() &&
+                cb.IsFunction()) {
+            Napi::Value argv[] = {
+                env.Null(),
+                Napi::Number::New(env, async->retrieved)
+            };
+            TRY_CATCH_CALL(async->stmt->Value(), cb, 2, argv);
+        }
+        uv_close(reinterpret_cast<uv_handle_t*>(handle), CloseCallback);
+    }
+}
+
+void Statement::Work_AfterEach(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<EachBaton> baton(static_cast<EachBaton*>(data));
+    auto* stmt = baton->stmt;
+
+    auto env = stmt->Env();
+    Napi::HandleScope scope(env);
+
+    if (stmt->status != SQLITE_DONE) {
+        Error(baton.get());
+    }
+
+    STATEMENT_END();
+}
+
+Napi::Value Statement::Reset(const Napi::CallbackInfo& info) {
+    auto env = info.Env();
+    Statement* stmt = this;
+
+    OPTIONAL_ARGUMENT_FUNCTION(0, callback);
+
+    auto* baton = new Baton(stmt, callback);
+    stmt->Schedule(Work_BeginReset, baton);
+
+    return info.This();
+}
+
+void Statement::Work_BeginReset(Baton* baton) {
+    STATEMENT_BEGIN(Reset);
+}
+
+void Statement::Work_Reset(napi_env e, void* data) {
+    STATEMENT_INIT(Baton);
+
+    sqlite3_reset(stmt->_handle);
+    stmt->status = SQLITE_OK;
+}
+
+void Statement::Work_AfterReset(napi_env e, napi_status status, void* data) {
+    std::unique_ptr<Baton> baton(static_cast<Baton*>(data));
+    auto* stmt = baton->stmt;
+
+    auto env = stmt->Env();
+    Napi::HandleScope scope(env);
+
+    // Fire callbacks.
+    Napi::Function cb = baton->callback.Value();
+    if (IS_FUNCTION(cb)) {
+        Napi::Value argv[] = { env.Null() };
+        TRY_CATCH_CALL(stmt->Value(), cb, 1, argv);
+    }
+
+    STATEMENT_END();
+}
+
+Napi::Value Statement::RowToJS(Napi::Env env, Row* row) {
+    Napi::EscapableHandleScope scope(env);
+
+    auto result = Napi::Object::New(env);
+
+    for (auto& field : *row) {
+
+        Napi::Value value;
+
+        switch (field->type) {
+            case SQLITE_INTEGER: {
+                value = Napi::Number::New(env, (static_cast<Values::Integer*>(field.get()))->value);
+            } break;
+            case SQLITE_FLOAT: {
+                value = Napi::Number::New(env, (static_cast<Values::Float*>(field.get()))->value);
+            } break;
+            case SQLITE_TEXT: {
+                value = Napi::String::New(env, (static_cast<Values::Text*>(field.get()))->value.c_str(), 
+                                               (static_cast<Values::Text*>(field.get()))->value.size());
+            } break;
+            case SQLITE_BLOB: {
+                value = Napi::Buffer<char>::Copy(env, (static_cast<Values::Blob*>(field.get()))->value, 
+                                                      (static_cast<Values::Blob*>(field.get()))->length);
+            } break;
+            case SQLITE_NULL: {
+                value = env.Null();
+            } break;
+        }
+
+        result.Set(field->name, value);
+    }
+
+    return scope.Escape(result);
+}
+
+void Statement::GetRow(Row* row, sqlite3_stmt* stmt) {
+    int cols = sqlite3_column_count(stmt);
+
+    for (int i = 0; i < cols; i++) {
+        int type = sqlite3_column_type(stmt, i);
+        const char* name = sqlite3_column_name(stmt, i);
+        if (name == NULL) {
+            assert(false);
+        }
+
+        switch (type) {
+            case SQLITE_INTEGER: {
+                row->emplace_back(std::make_unique<Values::Integer>(name, sqlite3_column_int64(stmt, i)));
+            }   break;
+            case SQLITE_FLOAT: {
+                row->emplace_back(std::make_unique<Values::Float>(name, sqlite3_column_double(stmt, i)));
+            }   break;
+            case SQLITE_TEXT: {
+                const char* text = (const char*)sqlite3_column_text(stmt, i);
+                int length = sqlite3_column_bytes(stmt, i);
+                row->emplace_back(std::make_unique<Values::Text>(name, length, text));
+            } break;
+            case SQLITE_BLOB: {
+                const void* blob = sqlite3_column_blob(stmt, i);
+                int length = sqlite3_column_bytes(stmt, i);
+                row->emplace_back(std::make_unique<Values::Blob>(name, length, blob));
+            }   break;
+            case SQLITE_NULL: {
+                row->emplace_back(std::make_unique<Values::Null>(name));
+            }   break;
+            default:
+                assert(false);
+        }
+    }
+}
+
+Napi::Value Statement::Finalize_(const Napi::CallbackInfo& info) {
+    auto env = info.Env();
+    Statement* stmt = this;
+    OPTIONAL_ARGUMENT_FUNCTION(0, callback);
+
+    auto *baton = new Baton(stmt, callback);
+    stmt->Schedule(Finalize_, baton);
+
+    return stmt->db->Value();
+}
+
+void Statement::Finalize_(Baton* b) {
+    auto baton = std::unique_ptr<Baton>(b);
+    auto env = baton->stmt->Env();
+    Napi::HandleScope scope(env);
+
+    baton->stmt->Finalize_();
+
+    // Fire callback in case there was one.
+    Napi::Function cb = baton->callback.Value();
+    if (IS_FUNCTION(cb)) {
+        TRY_CATCH_CALL(baton->stmt->Value(), cb, 0, NULL);
+    }
+}
+
+void Statement::Finalize_() {
+    assert(!finalized);
+    finalized = true;
+    CleanQueue();
+    // Finalize returns the status code of the last operation. We already fired
+    // error events in case those failed.
+    sqlite3_finalize(_handle);
+    _handle = NULL;
+    db->Unref();
+}
+
+void Statement::CleanQueue() {
+    auto env = this->Env();
+    Napi::HandleScope scope(env);
+
+    if (prepared && !queue.empty()) {
+        // This statement has already been prepared and is now finalized.
+        // Fire error for all remaining items in the queue.
+        EXCEPTION(Napi::String::New(env, "Statement is already finalized"), SQLITE_MISUSE, exception);
+        Napi::Value argv[] = { exception };
+        bool called = false;
+
+        // Clear out the queue so that this object can get GC'ed.
+        while (!queue.empty()) {
+            auto call = std::unique_ptr<Call>(queue.front());
+            queue.pop();
+
+            auto baton = std::unique_ptr<Baton>(call->baton);
+            Napi::Function cb = baton->callback.Value();
+
+            if (prepared && !cb.IsEmpty() &&
+                cb.IsFunction()) {
+                TRY_CATCH_CALL(Value(), cb, 1, argv);
+                called = true;
+            }
+        }
+
+        // When we couldn't call a callback function, emit an error on the
+        // Statement object.
+        if (!called) {
+            Napi::Value info[] = { Napi::String::New(env, "error"), exception };
+            EMIT_EVENT(Value(), 2, info);
+        }
+    }
+    else while (!queue.empty()) {
+        // Just delete all items in the queue; we already fired an event when
+        // preparing the statement failed.
+        auto call = std::unique_ptr<Call>(queue.front());
+        queue.pop();
+        // We don't call the actual callback, so we have to make sure that
+        // the baton gets destroyed.
+        delete call->baton;
+    }
+}