本文整理汇总了C++中Try::findByTarget方法的典型用法代码示例。如果您正苦于以下问题：C++ Try::findByTarget方法的具体用法？C++ Try::findByTarget怎么用？C++ Try::findByTarget使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类Try的用法示例。
在下文中一共展示了Try::findByTarget方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: Error
// Make sure the target directory allow device files (i.e., there no
// `nodev` on the mounted filesystem that contains the target path).
static Try<Nothing> ensureAllowDevices(const string& _targetDir)
{
// Mount table entries use realpaths. Therefore, we first get the
// realpath of the target directory.
Result<string> targetDir = os::realpath(_targetDir);
if (!targetDir.isSome()) {
return Error(
"Failed to get the realpath of '" + _targetDir + "': " +
(targetDir.isError() ? targetDir.error() : "Not found"));
}
Try<fs::MountInfoTable> table = fs::MountInfoTable::read();
if (table.isError()) {
return Error("Failed to get mount table: " + table.error());
}
// Trying to find the mount entry that contains the target
// directory. We achieve that by doing a reverse traverse of the
// mount table to find the first entry whose target is a prefix of
// the target directory.
Try<fs::MountInfoTable::Entry> targetDirMount =
table->findByTarget(_targetDir);
if (targetDirMount.isError()) {
return Error(
"Failed to find the mount containing '" + _targetDir +
"': " + targetDirMount.error());
}
// No need to do anything if the mount has no `nodev`.
if (!strings::contains(targetDirMount->vfsOptions, "nodev")) {
return Nothing();
}
if (targetDirMount->target != targetDir.get()) {
// This is the case where the target directory mount does not
// exist in the mount table (e.g., a new host running Mesos
// slave for the first time).
LOG(INFO) << "Self bind mounting '" << targetDir.get()
<< "' and remounting with '-o remount,dev'";
// NOTE: Instead of using fs::mount to perform the bind mount,
// we use the shell command here because the syscall 'mount'
// does not update the mount table (i.e., /etc/mtab). In other
// words, the mount will not be visible if the operator types
// command 'mount'. Since this mount will still be presented
// after all containers and the slave are stopped, it's better
// to make it visible. It's OK to use the blocking os::shell
// here because 'create' will only be invoked during
// initialization.
Try<string> mount = os::shell(
"mount --bind %s %s && "
"mount -o remount,dev %s",
targetDir.get(),
targetDir.get(),
targetDir.get());
if (mount.isError()) {
return Error(
"Failed to self bind mount '" + targetDir.get() +
"' and remount with '-o remount,dev': " + mount.error());
}
} else {
// This is the case where the target directory mount is in the
// mount table, but it's not remounted yet to remove 'nodev'
// (possibly due to slave crash while preparing the target
// directory mount). It's safe to re-do the following.
LOG(INFO) << "Remounting '" << targetDir.get() << "' with '-o remount,dev'";
Try<string> mount = os::shell(
"mount -o remount,dev %s",
targetDir.get());
if (mount.isError()) {
return Error(
"Failed to remount '" + targetDir.get() +
"' with '-o remount,dev': " + mount.error());
}
}
return Nothing();
}