Inheritance diagram for code::LinearBuffer:
Objects of this class have to be specifically opened after creation. They are destroyed when they go out of scope. To prevent such destruction, allocate them using "new" and destroy them using "delete". LinearBuffers allow you to transfer files and messages across a LAN and are especially useful when creating distributed processes. LinearBuffer supports threading, mostly by setting mutex locks to ensure data integrity. Open, close, read and write are all thread-safe. OpenW and functions that depend on the file pointer position are not. Trying to read/write a closed LB will provide an error. To obtain the meaning of the various error codes, check the file lb.h .
The name "yak:.OPUP/AT.log" corresponds to a remote LB stored on yak in the user's home directory i.e. to ~/.OPUP/AT.log. The name "AT.log" corresponds the LB stored in the current directory on the current machine. The LinearBuffer class presents an unified interface to both local and remote LBs.
Public Member Functions | |
| LinearBuffer () | |
| A LinearBuffer when constructed is an empty shell. | |
| virtual | ~LinearBuffer () |
| Will close the LB if needed. | |
| int | open (const URL &lb_url) |
| open() opens LB for reading. | |
| int | openW (const URL &lb_url) |
| Opens LB for writing if the LB exists. | |
| int | openW (const URL &lb_url, int numMessages, int avgSize) |
| A new LB is created if it doesn't already exist; if an LB of the same name already exists, the existing data is not clobbered. | |
| int | openOrCreate (const URL &lb_url) |
| Recommended form of openW() for applications to call. | |
| void | close () |
| close() closes LB if open. | |
| int | read (char *msg, int msgLength, LB_id_t msgId=LB_NEXT, int errorToSupress=0) |
| Reads message of specified id and returns the length of read-in message if successful. | |
| int | read (std::vector< char > &msg, LB_id_t msgId=LB_NEXT, int errorToSupress=0) |
| Identical to read(char*,int,LB_id_t,int) except the client doesn't need to know the size of the message beforehand. | |
| int | rewind () |
| Makes LB_NEXT point to the first message in the LB. | |
| int | latest () |
| Makes LB_NEXT point to the last message in the LB. | |
| int | moveLBptr (int offset) |
| Moves the LB pointer n messages from the current. | |
| int | seek (LB_id_t id, int offset) |
| Move the LB pointer to the specified message in the LB. | |
| void | write (const void *buffer, int bufferLength, int *setme_error=0) |
| Writes the buffer out to the LB as the latest message. | |
| void | write (int messageId, const void *buffer, int bufferLength, int *setme_error=0) |
| Same as write() except that the buffer overwrites the message messageId. | |
| LB_id_t | msgId () |
| msgId() returns the message id of last read/written message. | |
| const URL & | getLocation () const |
| Returns the name of the LB if already opened. | |
| bool | isOpen () const |
| Returns 1 if LB is open, 0 if not. | |
| int | getMessageLength (LB_id_t messageId) |
| Returns the length of the message. | |
| int | getLatestMsgInfo (LB_info &info) |
| Fills in the latest-written message id & its size in the LB. | |
| int | getAllMsgInfo (std::vector< LB_info > &setme) |
| Fills in information about all the messages currently in the LB. | |
| int | getLatestMsgInfo (std::vector< LB_info > &setme, size_t n_msgs) |
| Fills in information about all the latest N messages in the LB. | |
| code::LinearBuffer::LinearBuffer | ( | ) | [inline] |
A LinearBuffer when constructed is an empty shell.
Construction takes no arguments. To do anything with the LinearBuffer object, you need to call the member function open() or openW().
| virtual code::LinearBuffer::~LinearBuffer | ( | ) | [inline, virtual] |
Will close the LB if needed.
| void code::LinearBuffer::close | ( | ) |
close() closes LB if open.
This function is automatically called by the destructor.
| int code::LinearBuffer::getAllMsgInfo | ( | std::vector< LB_info > & | setme | ) |
Fills in information about all the messages currently in the LB.
| int code::LinearBuffer::getLatestMsgInfo | ( | std::vector< LB_info > & | setme, | |
| size_t | n_msgs | |||
| ) |
Fills in information about all the latest N messages in the LB.
| int code::LinearBuffer::getLatestMsgInfo | ( | LB_info & | info | ) |
Fills in the latest-written message id & its size in the LB.
See LB_info.
| const URL& code::LinearBuffer::getLocation | ( | ) | const [inline] |
Returns the name of the LB if already opened.
Undefined if the LB is not open already.
| int code::LinearBuffer::getMessageLength | ( | LB_id_t | messageId | ) |
Returns the length of the message.
| bool code::LinearBuffer::isOpen | ( | ) | const |
Returns 1 if LB is open, 0 if not.
| int code::LinearBuffer::latest | ( | ) | [inline] |
Makes LB_NEXT point to the last message in the LB.
Returns zero on success and a negative integer (see LB_seek) on error. Use lock() in a threaded application to keep the LB pointer where you have moved it.
| int code::LinearBuffer::moveLBptr | ( | int | offset | ) | [inline] |
Moves the LB pointer n messages from the current.
Negative n moves it back and postitive n moves it forward.Returns zero on success and a negative integer (see LB_seek) on error. Use lock() in a threaded application to keep the LB pointer where you have moved it
| LB_id_t code::LinearBuffer::msgId | ( | ) | [inline] |
msgId() returns the message id of last read/written message.
| int code::LinearBuffer::open | ( | const URL & | lb_url | ) |
open() opens LB for reading.
| int code::LinearBuffer::openOrCreate | ( | const URL & | lb_url | ) |
Recommended form of openW() for applications to call.
A new LB is created if it doesn't already exist; if an LB of the same name already exists, the existing data is not clobbered. Instead, a safer version of the open is performed. This function is not thread-safe. Pass in the expected numbers for number of messages and average size.
| int code::LinearBuffer::openW | ( | const URL & | lb_url, | |
| int | numMessages, | |||
| int | avgSize | |||
| ) |
A new LB is created if it doesn't already exist; if an LB of the same name already exists, the existing data is not clobbered.
Instead, a safer version of the open is performed. This function is not thread-safe. Pass in the expected numbers for number of messages and average size.
| int code::LinearBuffer::openW | ( | const URL & | lb_url | ) |
Opens LB for writing if the LB exists.
It does not create an LB.
| int code::LinearBuffer::read | ( | std::vector< char > & | msg, | |
| LB_id_t | msgId = LB_NEXT, |
|||
| int | errorToSupress = 0 | |||
| ) |
Identical to read(char*,int,LB_id_t,int) except the client doesn't need to know the size of the message beforehand.
| int code::LinearBuffer::read | ( | char * | msg, | |
| int | msgLength, | |||
| LB_id_t | msgId = LB_NEXT, |
|||
| int | errorToSupress = 0 | |||
| ) |
Reads message of specified id and returns the length of read-in message if successful.
The msg buffer should be large enough to hold msglen bytes. On failure, it returns a negative integer. For the meaning of these error codes, look at the documentation for LB_read. When the error to be suppressed is encountered, it returns zero.
Read using LB_NEXT is not thread-safe. Read using a message id is.
| int code::LinearBuffer::rewind | ( | ) | [inline] |
Makes LB_NEXT point to the first message in the LB.
Returns zero on success and a negative integer (see LB_seek) on error. Use lock() in a threaded application to keep the LB pointer where you have moved it.
| int code::LinearBuffer::seek | ( | LB_id_t | id, | |
| int | offset | |||
| ) | [inline] |
Move the LB pointer to the specified message in the LB.
Don't use this unless you know what you're doing. rewind(), latest(), and moveLBptr() are better for common use. Use lock() in a threaded application to keep the LB pointer where you have moved it.
| void code::LinearBuffer::write | ( | int | messageId, | |
| const void * | buffer, | |||
| int | bufferLength, | |||
| int * | setme_error = 0 | |||
| ) |
Same as write() except that the buffer overwrites the message messageId.
The replacing message should be the same size as the old one. Returns message id of the writen message on success and a negative number (see LB_write) on error.
| void code::LinearBuffer::write | ( | const void * | buffer, | |
| int | bufferLength, | |||
| int * | setme_error = 0 | |||
| ) |
Writes the buffer out to the LB as the latest message.
Returns message id of the writen message on success and a negative number (see LB_write) on error.
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