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#include <Iguana/Utilities/classlib/iobase/NamedPipeServer.h>
Public Member Functions | |
| virtual void | close (void) |
| virtual void | create (const std::string &name, FileAcl access=0666) |
| virtual void | create (const char *name, FileAcl access=0666) |
| virtual void | detach (void) |
| NamedPipeServer (const std::string &name, FileAcl access=0666) | |
| NamedPipeServer (const char *name, FileAcl access=0666) | |
| NamedPipeServer (void) | |
| virtual | ~NamedPipeServer (void) |
Private Member Functions | |
| NamedPipeServer (const NamedPipeServer &) | |
| NamedPipeServer & | operator= (const NamedPipeServer &) |
| void | sysclose (void) |
| void | sysdetach (void) |
| void | sysinit (const char *name, FileAcl access) |
Private Attributes | |
| IOFD | m_handle |
| std::string | m_name |
Named pipe is a named file system object, which when opened acts like a pipe channel (see Pipe). Unlike its anonymous counterpart Pipe, which has two ends linked together, reading and writing, a named pipe can be opened by, written to and read from by any number of processes. The file system name is merely a rendez-vous point, the data never passes through the file system.
Writes of less than FIXME bytes are atomic: they will not interleave with writes from other writers. Reads may return any amount of data, including data from multiple writers, except that writes of less than FIXME bytes are not interleaved (but can be merged on read). When multiple readers read from the same pipe, no guarantees are made on who receives which data.
Normally one would arrange to have one (server) open the pipe for read and one or more clients for writing. If more than one writer uses the pipe, one normally exchanges packets of size FIXME or less, with clear message boundaries (e.g. packets exactly of size FIXME or single lines of plain text). The server reads the data, splits it at message boundaries and the processes each message. To communicate back to the clients one can set up in each client another means communication, for example a named pipe that only that client listens to, and the name of which is passed to the server in each message.
NamedPipeServer is used only to create a named pipe; use File to establish a connection. The pipe may be opened for read or write (FIXME: or both? do all systems support this?). The pipe must be open at both ends before communication is possible; the open normally blocks until the other end is opened. If the pipe is opened in non-blocking mode (see IOFlags::OpenNonBlock flag), the call will not block; this succeeds for reading only if nobody else has the pipe open for writing, and for writing it will fail unless the other end has already been opened. In other words, the server must first open the pipe for read, and then the clients must open it write mode.
Writes to an unconnected pipe throw SystemError::PipeDisconnected error, or raise the SIGPIPE signal (if the signal is not blocked). Reads from an unconnected pipe, e.g. when all clients have closed the connection, return 0 to indicate end of connection.
Using named pipes portably is non-trivial despite encapsulation of the system interface provided by this and related clases. The semantics are sufficiently different on UNIX and Windows that the client code needs to be careful to work correctly. On UNIX, named pipes are real file system objects which can outlive the processes that create them. On Windows a named pipe exists only while a process holds a handle to it (= an instance of this class), and they are not real file system objects -- they are merely named as if they were files with a special convention that is incompatible with UNIX file system conventions: Windows pipes must be named \HOST where "HOST" can be "." for local pipes and NAME is the name of the pipe (with no slashes allowed).
FIXME: IOSelector support?
Definition at line 76 of file NamedPipeServer.h.
| lat::NamedPipeServer::NamedPipeServer | ( | void | ) |
| lat::NamedPipeServer::NamedPipeServer | ( | const char * | name, | |
| FileAcl | access = 0666 | |||
| ) |
| lat::NamedPipeServer::NamedPipeServer | ( | const std::string & | name, | |
| FileAcl | access = 0666 | |||
| ) |
| virtual lat::NamedPipeServer::~NamedPipeServer | ( | void | ) | [virtual] |
| lat::NamedPipeServer::NamedPipeServer | ( | const NamedPipeServer & | ) | [private] |
| virtual void lat::NamedPipeServer::create | ( | const std::string & | name, | |
| FileAcl | access = 0666 | |||
| ) | [virtual] |
| NamedPipeServer& lat::NamedPipeServer::operator= | ( | const NamedPipeServer & | ) | [private] |
IOFD lat::NamedPipeServer::m_handle [private] |
Definition at line 98 of file NamedPipeServer.h.
std::string lat::NamedPipeServer::m_name [private] |
Definition at line 99 of file NamedPipeServer.h.
1.5.4