Directly read file served from joedb_server. More...

#include <joedb/concurrency/Server_File.h>

Inheritance diagram for joedb::Server_File:

[legend]

Collaboration diagram for joedb::Server_File:

[legend]

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

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) 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

For very large reads, the returned value may be less than size, even if the end of the file is not reached. It is assumed that small reads (such as the 41 bytes of the joedb header) will not be truncated. 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.

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

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Server_File()

Member Function Documentation

◆ get_size()

◆ handshake()

◆ pread()

◆ pull()

◆ push()

◆ pwrite()