joedb::Server_File Class Reference

Directly read file served from joedb_server. More...

#include <joedb/concurrency/Server_File.h>

Inheritance diagram for joedb::Server_File:

Collaboration diagram for joedb::Server_File:

Public Member Functions
	Server_File (const Connector &connector, Logger &logger=Logger::dummy_logger)
int64_t	handshake (const Readonly_Journal &client_journal, Content_Check content_check) override
	Called during Client construction.
int64_t	pull (Lock_Action lock_action, Data_Transfer data_transfer, Writable_Journal &client_journal, std::chrono::milliseconds wait) override
	Pull from the connection.
int64_t	push (const Readonly_Journal &client_journal, int64_t server_position, int64_t until_position, Unlock_Action unlock_action) override
	Push new data to the connection.
size_t	pread (char *data, size_t size, int64_t offset) const override
	Read a range of bytes.
void	pwrite (const char *data, size_t size, int64_t offset) override
	Write a range of bytes. Extend file size if necessary.
int64_t	get_size () const override
	Get the size of the file, or -1 if it is unknown.
Public Member Functions inherited from joedb::Robust_Connection
	Robust_Connection (const Connector &connector, Logger &logger)
size_t	pread (char *data, size_t size, int64_t offset) const
void	unlock () override
	Unlock the connection.
bool	is_pullonly () const override
Public Member Functions inherited from joedb::Connection
virtual	~Connection ()
Public Member Functions inherited from joedb::Abstract_File
	Abstract_File (Open_Mode mode)
bool	is_shared () const noexcept
bool	is_readonly () const noexcept
Open_Mode	get_mode () const noexcept
void	full_pread (char *data, size_t size, int64_t offset) const
	Fill the buffer, or throw if the end of the file is reached.
virtual void	sync ()
	Write data durably (including file-size change).
virtual void	datasync ()
	Write data durably (no file-size change).
virtual void	shared_lock (int64_t start, int64_t size)
	Lock a range of bytes for reading (prevents writes, not reads).
virtual void	exclusive_lock (int64_t start, int64_t size)
	Lock a range of bytes for writing (prevents both writes and reads).
virtual void	unlock (int64_t start, int64_t size) noexcept
	Remove a lock. The range should match the range of a corresponding lock.
void	exclusive_lock_tail ()
void	unlock_tail () noexcept
void	exclusive_lock_head ()
void	shared_lock_head ()
void	unlock_head () noexcept
std::string	read_blob (Blob blob, int64_t max_size=-1) const
virtual void	copy_to (Abstract_File &destination, int64_t start, int64_t size) const
virtual bool	equal_to (const Abstract_File &destination, int64_t from, int64_t until) const
void	copy_to (Abstract_File &destination) const
virtual	~Abstract_File ()=default

Additional Inherited Members
Static Public Member Functions inherited from joedb::Abstract_File
static void	reading_past_end_of_file ()
Static Public Attributes inherited from joedb::Connection
static Connection	dummy
	Since this class has no internal state, this global variable can be used instead of creating an instance.
Protected Member Functions inherited from joedb::Robust_Connection
void	reconnect (const std::exception *e) const
template<typename F>
auto	try_until_success (const F &f) const
Protected Member Functions inherited from joedb::Connection
	Connection ()=default
Protected Member Functions inherited from joedb::Abstract_File
void	make_readonly ()
void	make_writable ()
Static Protected Member Functions inherited from joedb::Connection
static void	content_mismatch ()
	Called by handshake when the file and the connection do not match.
Protected Attributes inherited from joedb::Robust_Connection
std::unique_ptr< Server_Connection >	connection
Static Protected Attributes inherited from joedb::Abstract_File
static constexpr int64_t	last_position = (1ULL << 63) - 1

Detailed Description

This class allows reading a remote file via the joedb network protocol. It is convenient for reading blobs from a large remote database without having to download a local replica. This file can also be written to: the head and tail of the file are stored in RAM locally, and can be pushed to the remote server if used in a client.

#include "joedb/concurrency/Local_Connector.h"
#include "joedb/concurrency/Server_File.h"
#include "joedb/concurrency/Writable_Journal_Client.h"
 
#include <iostream>
 
int main()
{
 joedb::Local_Connector connector("blobs.joedb.sock");
 joedb::Server_File server_file(connector);
 joedb::Writable_Journal_Client client(server_file, server_file);
 
 const auto blob = client.transaction([](joedb::Writable_Journal &journal)
 {
  return journal.write_blob("blob");
 });
 
 std::cout << server_file.read_blob(blob) << '\n';
 
 return 0;
}

Definition at line 21 of file Server_File.h.

Constructor & Destructor Documentation

Server_File()

joedb::Server_File::Server_File	(	const Connector &	connector,
		Logger &	logger = Logger::dummy_logger )

Definition at line 21 of file Server_File.cpp.

Member Function Documentation

get_size()

int64_t joedb::Server_File::get_size ( ) const

inlineoverridevirtual

Reimplemented from joedb::Abstract_File.

Definition at line 69 of file Server_File.h.

handshake()

int64_t joedb::Server_File::handshake ( const Readonly_Journal & client_journal, Content_Check content_check )

overridevirtual

Parameters

client_journal	may be used to check matching content
content_check	indicates how matching content is tested

Returns

connection checkpoint

Reimplemented from joedb::Robust_Connection.

Definition at line 62 of file Server_File.cpp.

pread()

size_t joedb::Server_File::pread ( char * data, size_t size, int64_t offset ) const

overridevirtual

The returned value may be less than size, even if the end of the file is not reached. 0 is returned if the end of the file is reached.

Reimplemented from joedb::Abstract_File.

Definition at line 104 of file Server_File.cpp.

pull()

int64_t joedb::Server_File::pull ( Lock_Action lock_action, Data_Transfer data_transfer, Writable_Journal & client_journal, std::chrono::milliseconds wait )

overridevirtual

Parameters

lock_action	whether the connection should be locked before pulling
data_transfer	whether data should be transferred
client_journal	journal to pull into
wait	duration during which the connection may wait for new data if the pull would otherwise be empty

Returns

connection checkpoint

Reimplemented from joedb::Robust_Connection.

Definition at line 34 of file Server_File.cpp.

push()

int64_t joedb::Server_File::push ( const Readonly_Journal & client_journal, int64_t from, int64_t until, Unlock_Action unlock_action )

overridevirtual

Returns

connection checkpoint

Reimplemented from joedb::Robust_Connection.

Definition at line 75 of file Server_File.cpp.

pwrite()

void joedb::Server_File::pwrite ( const char * data, size_t size, int64_t offset )

overridevirtual

Reimplemented from joedb::Abstract_File.

Definition at line 117 of file Server_File.cpp.

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The documentation for this class was generated from the following files:

• /home/rcoulom/repos/joedb/src/joedb/concurrency/Server_File.h
• /home/rcoulom/repos/joedb/src/joedb/concurrency/Server_File.cpp