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Bug 1651016 - Introduce QM_TRY and QM_TRY_VAR macros; r=dom-workers-and-storage-reviewers,ttung,sg 

Differential Revision: https://phabricator.services.mozilla.com/D83927
This commit is contained in:
Jan Varga 2020-07-24 07:11:24 +00:00
Родитель 2369b54b63
Коммит 7ae4b87c84
4 изменённых файлов: 421 добавлений и 0 удалений
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12
dom/quota/QuotaCommon.cpp
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@ -172,6 +172,18 @@ Result<bool, nsresult> WarnIfFileIsUnknown(nsIFile& aFile,
}
#endif
void HandleError(const nsLiteralCString& aExpr,
const nsLiteralCString& aSourceFile, int32_t aSourceLine) {
#ifdef DEBUG
NS_DebugBreak(NS_DEBUG_WARNING, "Error", aExpr.get(), aSourceFile.get(),
aSourceLine);
#endif
// TODO: Report to browser console
// TODO: Report to telemetry
}
} // namespace quota
} // namespace dom
} // namespace mozilla

252
dom/quota/QuotaCommon.h
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@ -13,6 +13,10 @@
#include "nsString.h"
#include "nsTArray.h"
// TODO: Maybe move this to mfbt/MacroArgs.h
#define MOZ_ARG_4(a1, a2, a3, a4, ...) a4
#define MOZ_ARG_5(a1, a2, a3, a4, a5, ...) a5
#define BEGIN_QUOTA_NAMESPACE \
namespace mozilla { \
namespace dom { \
@ -52,6 +56,251 @@
# define WARN_IF_FILE_IS_UNKNOWN(_file) Result<bool, nsresult>(false)
#endif
/**
* There are multiple ways to handle unrecoverable conditions:
* 1. Using NS_ENSURE_* macros
*
* Mainly:
* - NS_ENSURE_SUCCESS
* - NS_ENSURE_SUCCESS_VOID
* - NS_ENSURE_TRUE
* - NS_ENSURE_TRUE_VOID
*
* Typical use cases:
*
* nsresult MyFunc1(nsIFile& aFile) {
* bool exists;
* nsresult rv = aFile.Exists(&exists);
* NS_ENSURE_SUCCESS(rv, rv);
* NS_ENSURE_TRUE(exists, NS_ERROR_FAILURE);
*
* return NS_OK;
* }
*
* nsresult MyFunc2(nsIFile& aFile) {
* bool exists;
* nsresult rv = aFile.Exists(&exists);
* NS_ENSURE_SUCCESS(rv, NS_ERROR_UNEXPECTED);
* NS_ENSURE_TRUE(exists, NS_ERROR_UNEXPECTED);
*
* return NS_OK;
* }
*
* void MyFunc3(nsIFile& aFile) {
* bool exists;
* nsresult rv = aFile.Exists(&exists);
* NS_ENSURE_SUCCESS_VOID(rv);
* NS_ENSURE_TRUE_VOID(exists);
* }
*
* 2. Using NS_WARN_IF macro with own control flow handling
*
* Typical use cases:
*
* nsresult MyFunc1(nsIFile& aFile) {
* bool exists;
* nsresult rv = aFile.Exists(&exists);
* if (NS_WARN_IF(NS_FAILED(rv)) {
* return rv;
* }
* if (NS_WARN_IF(!exists) {
* return NS_ERROR_FAILURE;
* }
*
* return NS_OK;
* }
*
* nsresult MyFunc2(nsIFile& aFile) {
* bool exists;
* nsresult rv = aFile.Exists(&exists);
* if (NS_WARN_IF(NS_FAILED(rv)) {
* return NS_ERROR_UNEXPECTED;
* }
* if (NS_WARN_IF(!exists) {
* return NS_ERROR_UNEXPECTED;
* }
*
* return NS_OK;
* }
*
* void MyFunc3(nsIFile& aFile) {
* bool exists;
* nsresult rv = aFile.Exists(&exists);
* if (NS_WARN_IF(NS_FAILED(rv)) {
* return;
* }
* if (NS_WARN_IF(!exists) {
* return;
* }
* }
*
* 3. Using MOZ_TRY/MOZ_TRY_VAR macros
*
* Typical use cases:
*
* nsresult MyFunc1(nsIFile& aFile) {
* bool exists;
* MOZ_TRY(aFile.Exists(&exists));
* // Note, exists can't be checked directly using MOZ_TRY without the Result
* // extension defined in quota manager
* MOZ_TRY(OkIf(exists), NS_ERROR_FAILURE);
*
* return NS_OK;
* }
*
* nsresult MyFunc2(nsIFile& aFile) {
* // MOZ_TRY can't return a custom return value
*
* return NS_OK;
* }
*
* void MyFunc3(nsIFile& aFile) {
* // MOZ_TRY can't return void
* }
*
* 4. Using QM_TRY/QM_TRY_VAR macros (Quota manager specific, defined below)
*
* Typical use cases:
*
* nsresult MyFunc1(nsIFile& aFile) {
* bool exists;
* QM_TRY(aFile.Exists(&exists));
* QM_TRY(OkIf(exists), NS_ERROR_FAILURE);
*
* return NS_OK;
* }
*
* nsresult MyFunc2(nsIFile& aFile) {
* bool exists;
* QM_TRY(aFile.Exists(&exists), NS_ERROR_UNEXPECTED);
* QM_TRY(OkIf(exists), NS_ERROR_UNEXPECTED);
*
* return NS_OK;
* }
*
* void MyFunc3(nsIFile& aFile) {
* bool exists;
* QM_TRY(aFile.Exists(&exists), QM_VOID);
* QM_TRY(OkIf(exists), QM_VOID);
* }
*
* QM_TRY/QM_TRY_VAR is like MOZ_TRY/MOZ_TRY_VAR but if an error occurs it
* additionally calls a generic function HandleError to handle the error and it
* can be used to return custom return values as well.
* HandleError currently only warns in debug builds, it will report to the
* browser console and telemetry in the future.
* The other advantage of QM_TRY/QM_TRY_VAR is that a local nsresult is not
* needed at all in all cases, all calls can be wrapped directly. If an error
* occurs, the warning contains a concrete call instead of the rv local
* variable. For example:
*
* 1. WARNING: NS_ENSURE_SUCCESS(rv, rv) failed with result 0x80004005
* (NS_ERROR_FAILURE): file XYZ, line N
*
* 2. WARNING: 'NS_FAILED(rv)', file XYZ, line N
*
* 3. Nothing (MOZ_TRY doesn't warn)
*
* 4. WARNING: Error: 'aFile.Exists(&exists)', file XYZ, line N
*
* It's highly recommended to use QM_TRY/QM_TRY_VAR in new code for quota
* manager and quota clients. Existing code should be incrementally converted
* as needed.
*
* QM_TRY_VOID/QM_TRY_VAR_VOID is not defined on purpose since it's possible to
* use QM_TRY/QM_TRY_VAR even in void functions. However, QM_TRY(Task(), )
* would look odd so it's recommended to use a dummy define QM_VOID that
* evaluates to nothing instead: QM_TRY(Task(), QM_VOID)
*/
#define QM_VOID
// QM_TRY_MISSING_ARGS, QM_TRY_PROPAGATE_ERR and QM_TRY_CUSTOM_RET_VAR macros
// are implementation details of QM_TRY and shouldn't be used directly.
#define QM_TRY_MISSING_ARGS(...) \
do { \
static_assert(false, "Did you forget arguments to QM_TRY?"); \
} while (0)
// Handles the one arg case when the eror is propagated.
#define QM_TRY_PROPAGATE_ERR(expr) \
do { \
auto mozTryTempResult_ = ::mozilla::ToResult(expr); \
if (MOZ_UNLIKELY(mozTryTempResult_.isErr())) { \
mozilla::dom::quota::HandleError(nsLiteralCString(#expr), \
nsLiteralCString(__FILE__), __LINE__); \
return mozTryTempResult_.propagateErr(); \
} \
} while (0)
// Handles the two args case when a custom return value needs to be returned
#define QM_TRY_CUSTOM_RET_VAR(expr, customRetVal) \
do { \
auto mozTryTempResult_ = ::mozilla::ToResult(expr); \
if (MOZ_UNLIKELY(mozTryTempResult_.isErr())) { \
mozilla::dom::quota::HandleError(nsLiteralCString(#expr), \
nsLiteralCString(__FILE__), __LINE__); \
return customRetVal; \
} \
} while (0)
/**
* QM_TRY(expr[, customRetVal]) is the C++ equivalent of Rust's `try!(expr);`.
* First, it evaluates expr, which must produce a Result value. On success, it
* discards the result altogether. On error, it calls HandleError and returns
* an error Result from the enclosing function or a custom return value (if the
* second arg was passed).
*/
#define QM_TRY(...) \
MOZ_ARG_4(, ##__VA_ARGS__, QM_TRY_CUSTOM_RET_VAR(__VA_ARGS__), \
QM_TRY_PROPAGATE_ERR(__VA_ARGS__), \
QM_TRY_MISSING_ARGS(__VA_ARGS__))
// QM_TRY_VAR_MISSING_ARGS, QM_TRY_VAR_PROPAGATE_ERR and
// QM_TRY_VAR_CUSTOM_RET_VAR macros are implementation details of QM_TRY_VAR
// and shouldn't be used directly.
#define QM_TRY_VAR_MISSING_ARGS(...) \
do { \
static_assert(false, "Did you forget arguments to QM_TRY_VAR?"); \
} while (0)
// Handles the two args case when the eror is propagated.
#define QM_TRY_VAR_PROPAGATE_ERR(target, expr) \
do { \
auto mozTryVarTempResult_ = (expr); \
if (MOZ_UNLIKELY(mozTryVarTempResult_.isErr())) { \
mozilla::dom::quota::HandleError(nsLiteralCString(#expr), \
nsLiteralCString(__FILE__), __LINE__); \
return mozTryVarTempResult_.propagateErr(); \
} \
(target) = mozTryVarTempResult_.unwrap(); \
} while (0)
// Handles the three args case when a custom return value needs to be returned
#define QM_TRY_VAR_CUSTOM_RET_VAR(target, expr, customRetVal) \
do { \
auto mozTryVarTempResult_ = (expr); \
if (MOZ_UNLIKELY(mozTryVarTempResult_.isErr())) { \
mozilla::dom::quota::HandleError(nsLiteralCString(#expr), \
nsLiteralCString(__FILE__), __LINE__); \
return customRetVal; \
} \
(target) = mozTryVarTempResult_.unwrap(); \
} while (0)
/**
* QM_TRY_VAR(target, expr[, customRetVal]) is the C++ equivalent of Rust's
* `target = try!(expr);`. First, it evaluates expr, which must produce a
* Result value. On success, the result's success value is assigned to target.
* On error, it calls HandleError and returns the error result or a custom
* return value (if the third arg was passed). |target| must be an lvalue.
*/
#define QM_TRY_VAR(...) \
MOZ_ARG_5(, ##__VA_ARGS__, QM_TRY_VAR_CUSTOM_RET_VAR(__VA_ARGS__), \
QM_TRY_VAR_PROPAGATE_ERR(__VA_ARGS__), \
QM_TRY_VAR_MISSING_ARGS(__VA_ARGS__), \
QM_TRY_VAR_MISSING_ARGS(__VA_ARGS__))
// Telemetry probes to collect number of failure during the initialization.
#ifdef NIGHTLY_BUILD
# define REPORT_TELEMETRY_INIT_ERR(_key, _label) \
@ -202,6 +451,9 @@ Result<bool, nsresult> WarnIfFileIsUnknown(nsIFile& aFile,
int32_t aSourceLine);
#endif
void HandleError(const nsLiteralCString& aExpr,
const nsLiteralCString& aSourceFile, int32_t aSourceLine);
} // namespace quota
} // namespace dom
} // namespace mozilla

156
dom/quota/test/gtest/TestQuotaCommon.cpp Normal file
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@ -0,0 +1,156 @@
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "gtest/gtest.h"
#include "mozilla/dom/quota/QuotaCommon.h"
#include "mozilla/ResultExtensions.h"
using namespace mozilla;
using namespace mozilla::dom::quota;
TEST(QuotaCommon_Try, Success)
{
bool flag = false;
nsresult rv = [&]() -> nsresult {
QM_TRY(NS_OK);
flag = true;
return NS_OK;
}();
EXPECT_EQ(rv, NS_OK);
EXPECT_TRUE(flag);
}
TEST(QuotaCommon_Try, Failure_PropagateErr)
{
bool flag = false;
nsresult rv = [&]() -> nsresult {
QM_TRY(NS_ERROR_FAILURE);
flag = true;
return NS_OK;
}();
EXPECT_EQ(rv, NS_ERROR_FAILURE);
EXPECT_FALSE(flag);
}
TEST(QuotaCommon_Try, Failure_CustomErr)
{
bool flag = false;
nsresult rv = [&]() -> nsresult {
QM_TRY(NS_ERROR_FAILURE, NS_ERROR_UNEXPECTED);
flag = true;
return NS_OK;
}();
EXPECT_EQ(rv, NS_ERROR_UNEXPECTED);
EXPECT_FALSE(flag);
}
TEST(QuotaCommon_Try, Failure_NoErr)
{
bool flag = false;
[&]() -> void {
QM_TRY(NS_ERROR_FAILURE, QM_VOID);
flag = true;
}();
EXPECT_FALSE(flag);
}
TEST(QuotaCommon_TryVar, Success)
{
bool flag = false;
nsresult rv = [&]() -> nsresult {
auto task = []() -> Result<int32_t, nsresult> { return 42; };
int32_t x = 0;
QM_TRY_VAR(x, task());
EXPECT_EQ(x, 42);
flag = true;
return NS_OK;
}();
EXPECT_EQ(rv, NS_OK);
EXPECT_TRUE(flag);
}
TEST(QuotaCommon_TryVar, Failure_PropagateErr)
{
bool flag = false;
nsresult rv = [&]() -> nsresult {
auto task = []() -> Result<int32_t, nsresult> {
return Err(NS_ERROR_FAILURE);
};
int32_t x = 0;
QM_TRY_VAR(x, task());
EXPECT_EQ(x, 0);
flag = true;
return NS_OK;
}();
EXPECT_EQ(rv, NS_ERROR_FAILURE);
EXPECT_FALSE(flag);
}
TEST(QuotaCommon_TryVar, Failure_CustomErr)
{
bool flag = false;
nsresult rv = [&]() -> nsresult {
auto task = []() -> Result<int32_t, nsresult> {
return Err(NS_ERROR_FAILURE);
};
int32_t x = 0;
QM_TRY_VAR(x, task(), NS_ERROR_UNEXPECTED);
EXPECT_EQ(x, 0);
flag = true;
return NS_OK;
}();
EXPECT_EQ(rv, NS_ERROR_UNEXPECTED);
EXPECT_FALSE(flag);
}
TEST(QuotaCommon_TryVar, Failure_NoErr)
{
bool flag = false;
[&]() -> void {
auto task = []() -> Result<int32_t, nsresult> {
return Err(NS_ERROR_FAILURE);
};
int32_t x = 0;
QM_TRY_VAR(x, task(), QM_VOID);
EXPECT_EQ(x, 0);
flag = true;
}();
EXPECT_FALSE(flag);
}

1
dom/quota/test/gtest/moz.build
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@ -7,6 +7,7 @@
UNIFIED_SOURCES = [
'TestCheckedUnsafePtr.cpp',
'TestEncryptedStream.cpp',
'TestQuotaCommon.cpp',
'TestQuotaManager.cpp',
'TestUsageInfo.cpp',
]