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db/simple: mount points

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A SimpleDatabase instance can now "mount" other Database instances at
certain locations.  This is used to use a new SimpleDatabase instance
for each storage mount (issued with the "mount" protocol command).
Each such instance has its own database file, stored in the directory
that is specified with the "cache_directory" option.
This commit is contained in:
Max Kellermann
2014-02-26 08:39:44 +01:00
parent 2a16fc74fd
commit e9a85aa4e4
19 changed files with 603 additions and 24 deletions
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4
src/command/CommandError.cxx
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@@ -112,6 +112,10 @@ print_error(Client &client, const Error &error)
case DB_NOT_FOUND:
command_error(client, ACK_ERROR_NO_EXIST, "Not found");
return CommandResult::ERROR;
case DB_CONFLICT:
command_error(client, ACK_ERROR_ARG, "Conflict");
return CommandResult::ERROR;
}
#endif
} else if (error.IsDomain(errno_domain)) {

47
src/command/StorageCommands.cxx
View File

@@ -29,6 +29,8 @@
#include "Instance.hxx"
#include "storage/Registry.hxx"
#include "storage/CompositeStorage.hxx"
#include "db/plugins/simple/SimpleDatabasePlugin.hxx"
#include "db/update/Service.hxx"
#include "Idle.hxx"
static void
@@ -98,6 +100,16 @@ handle_mount(Client &client, gcc_unused int argc, char *argv[])
return CommandResult::ERROR;
}
if (strchr(local_uri, '/') != nullptr) {
/* allow only top-level mounts for now */
/* TODO: eliminate this limitation after ensuring that
UpdateQueue::Erase() really gets called for every
unmount, and no Directory disappears recursively
during database update */
command_error(client, ACK_ERROR_ARG, "Bad mount point");
return CommandResult::ERROR;
}
Error error;
Storage *storage = CreateStorageURI(remote_uri, error);
if (storage == nullptr) {
@@ -111,6 +123,23 @@ handle_mount(Client &client, gcc_unused int argc, char *argv[])
composite.Mount(local_uri, storage);
idle_add(IDLE_MOUNT);
#ifdef ENABLE_DATABASE
Database *_db = client.partition.instance.database;
if (_db != nullptr && _db->IsPlugin(simple_db_plugin)) {
SimpleDatabase &db = *(SimpleDatabase *)_db;
if (!db.Mount(local_uri, remote_uri, error)) {
composite.Unmount(local_uri);
return print_error(client, error);
}
// TODO: call Instance::OnDatabaseModified()?
// TODO: trigger database update?
idle_add(IDLE_DATABASE);
}
#endif
return CommandResult::OK;
}
@@ -132,11 +161,29 @@ handle_unmount(Client &client, gcc_unused int argc, char *argv[])
return CommandResult::ERROR;
}
#ifdef ENABLE_DATABASE
if (client.partition.instance.update != nullptr)
/* ensure that no database update will attempt to work
with the database/storage instances we're about to
destroy here */
client.partition.instance.update->CancelMount(local_uri);
Database *_db = client.partition.instance.database;
if (_db != nullptr && _db->IsPlugin(simple_db_plugin)) {
SimpleDatabase &db = *(SimpleDatabase *)_db;
if (db.Unmount(local_uri))
// TODO: call Instance::OnDatabaseModified()?
idle_add(IDLE_DATABASE);
}
#endif
if (!composite.Unmount(local_uri)) {
command_error(client, ACK_ERROR_ARG, "Not a mount point");
return CommandResult::ERROR;
}
idle_add(IDLE_MOUNT);
return CommandResult::OK;
}