tchdb.3

Tokyo Cabinet的Tokyo Cabinet 是一个DBM的实现。这里的数据库由一系列key-value对的记录构成。key和value都可以是任意长度的字节序列,既可以是二进制也可以是字符

.TH "TCHDB" 3 "2009-02-13" "Man Page" "Tokyo Cabinet"

.SH NAME
tchdb \- the hash database API

.SH DESCRIPTION
.PP
Hash database is a file containing a hash table and is handled with the hash database API.
.PP
To use the hash database API, include `\fBtcutil.h\fR', `\fBtchdb.h\fR', and related standard header files.  Usually, write the following description near the front of a source file.
.PP
.RS
.br
\fB#include <tcutil.h>\fR
.br
\fB#include <tchdb.h>\fR
.br
\fB#include <stdlib.h>\fR
.br
\fB#include <time.h>\fR
.br
\fB#include <stdbool.h>\fR
.br
\fB#include <stdint.h>\fR
.RE
.PP
Objects whose type is pointer to `\fBTCHDB\fR' are used to handle hash databases.  A hash database object is created with the function `\fBtchdbnew\fR' and is deleted with the function `\fBtchdbdel\fR'.  To avoid memory leak, it is important to delete every object when it is no longer in use.
.PP
Before operations to store or retrieve records, it is necessary to open a database file and connect the hash database object to it.  The function `\fBtchdbopen\fR' is used to open a database file and the function `\fBtchdbclose\fR' is used to close the database file.  To avoid data missing or corruption, it is important to close every database file when it is no longer in use.

.SH API
.PP
The function `tchdberrmsg' is used in order to get the message string corresponding to an error code.
.PP
.RS
.br
\fBconst char *tchdberrmsg(int \fIecode\fB);\fR
.RS
`\fIecode\fR' specifies the error code.
.RE
.RS
The return value is the message string of the error code.
.RE
.RE
.PP
The function `tchdbnew' is used in order to create a hash database object.
.PP
.RS
.br
\fBTCHDB *tchdbnew(void);\fR
.RS
The return value is the new hash database object.
.RE
.RE
.PP
The function `tchdbdel' is used in order to delete a hash database object.
.PP
.RS
.br
\fBvoid tchdbdel(TCHDB *\fIhdb\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object.
.RE
.RS
If the database is not closed, it is closed implicitly.  Note that the deleted object and its derivatives can not be used anymore.
.RE
.RE
.PP
The function `tchdbecode' is used in order to get the last happened error code of a hash database object.
.PP
.RS
.br
\fBint tchdbecode(TCHDB *\fIhdb\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object.
.RE
.RS
The return value is the last happened error code.
.RE
.RS
The following error codes are defined: `TCESUCCESS' for success, `TCETHREAD' for threading error, `TCEINVALID' for invalid operation, `TCENOFILE' for file not found, `TCENOPERM' for no permission, `TCEMETA' for invalid meta data, `TCERHEAD' for invalid record header, `TCEOPEN' for open error, `TCECLOSE' for close error, `TCETRUNC' for trunc error, `TCESYNC' for sync error, `TCESTAT' for stat error, `TCESEEK' for seek error, `TCEREAD' for read error, `TCEWRITE' for write error, `TCEMMAP' for mmap error, `TCELOCK' for lock error, `TCEUNLINK' for unlink error, `TCERENAME' for rename error, `TCEMKDIR' for mkdir error, `TCERMDIR' for rmdir error, `TCEKEEP' for existing record, `TCENOREC' for no record found, and `TCEMISC' for miscellaneous error.
.RE
.RE
.PP
The function `tchdbsetmutex' is used in order to set mutual exclusion control of a hash database object for threading.
.PP
.RS
.br
\fBbool tchdbsetmutex(TCHDB *\fIhdb\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object which is not opened.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
Note that the mutual exclusion control of the database should be set before the database is opened.
.RE
.RE
.PP
The function `tchdbtune' is used in order to set the tuning parameters of a hash database object.
.PP
.RS
.br
\fBbool tchdbtune(TCHDB *\fIhdb\fB, int64_t \fIbnum\fB, int8_t \fIapow\fB, int8_t \fIfpow\fB, uint8_t \fIopts\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object which is not opened.
.RE
.RS
`\fIbnum\fR' specifies the number of elements of the bucket array.  If it is not more than 0, the default value is specified.  The default value is 16381.  Suggested size of the bucket array is about from 0.5 to 4 times of the number of all records to be stored.
.RE
.RS
`\fIapow\fR' specifies the size of record alignment by power of 2.  If it is negative, the default value is specified.  The default value is 4 standing for 2^4=16.
.RE
.RS
`\fIfpow\fR' specifies the maximum number of elements of the free block pool by power of 2.  If it is negative, the default value is specified.  The default value is 10 standing for 2^10=1024.
.RE
.RS
`\fIopts\fR' specifies options by bitwise-or: `HDBTLARGE' specifies that the size of the database can be larger than 2GB by using 64\-bit bucket array, `HDBTDEFLATE' specifies that each record is compressed with Deflate encoding, `HDBTBZIP' specifies that each record is compressed with BZIP2 encoding, `HDBTTCBS' specifies that each record is compressed with TCBS encoding.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
Note that the tuning parameters should be set before the database is opened.
.RE
.RE
.PP
The function `tchdbsetcache' is used in order to set the caching parameters of a hash database object.
.PP
.RS
.br
\fBbool tchdbsetcache(TCHDB *\fIhdb\fB, int32_t \fIrcnum\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object which is not opened.
.RE
.RS
`\fIrcnum\fR' specifies the maximum number of records to be cached.  If it is not more than 0, the record cache is disabled.  It is disabled by default.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
Note that the caching parameters should be set before the database is opened.
.RE
.RE
.PP
The function `tchdbsetxmsiz' is used in order to set the size of the extra mapped memory of a hash database object.
.PP
.RS
.br
\fBbool tchdbsetxmsiz(TCHDB *\fIhdb\fB, int64_t \fIxmsiz\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object which is not opened.
.RE
.RS
`\fIxmsiz\fR' specifies the size of the extra mapped memory.  If it is not more than 0, the extra mapped memory is disabled.  The default size is 67108864.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
Note that the mapping parameters should be set before the database is opened.
.RE
.RE
.PP
The function `tchdbopen' is used in order to open a database file and connect a hash database object.
.PP
.RS
.br
\fBbool tchdbopen(TCHDB *\fIhdb\fB, const char *\fIpath\fB, int \fIomode\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object which is not opened.
.RE
.RS
`\fIpath\fR' specifies the path of the database file.
.RE
.RS
`\fIomode\fR' specifies the connection mode: `HDBOWRITER' as a writer, `HDBOREADER' as a reader.  If the mode is `HDBOWRITER', the following may be added by bitwise-or: `HDBOCREAT', which means it creates a new database if not exist, `HDBOTRUNC', which means it creates a new database regardless if one exists, `HDBOTSYNC', which means every transaction synchronizes updated contents with the device.  Both of `HDBOREADER' and `HDBOWRITER' can be added to by bitwise-or: `HDBONOLCK', which means it opens the database file without file locking, or `HDBOLCKNB', which means locking is performed without blocking.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RE
.PP
The function `tchdbclose' is used in order to close a hash database object.
.PP
.RS
.br
\fBbool tchdbclose(TCHDB *\fIhdb\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
Update of a database is assured to be written when the database is closed.  If a writer opens a database but does not close it appropriately, the database will be broken.
.RE
.RE
.PP
The function `tchdbput' is used in order to store a record into a hash database object.
.PP
.RS
.br
\fBbool tchdbput(TCHDB *\fIhdb\fB, const void *\fIkbuf\fB, int \fIksiz\fB, const void *\fIvbuf\fB, int \fIvsiz\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkbuf\fR' specifies the pointer to the region of the key.
.RE
.RS
`\fIksiz\fR' specifies the size of the region of the key.
.RE
.RS
`\fIvbuf\fR' specifies the pointer to the region of the value.
.RE
.RS
`\fIvsiz\fR' specifies the size of the region of the value.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
If a record with the same key exists in the database, it is overwritten.
.RE
.RE
.PP
The function `tchdbput2' is used in order to store a string record into a hash database object.
.PP
.RS
.br
\fBbool tchdbput2(TCHDB *\fIhdb\fB, const char *\fIkstr\fB, const char *\fIvstr\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkstr\fR' specifies the string of the key.
.RE
.RS
`\fIvstr\fR' specifies the string of the value.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
If a record with the same key exists in the database, it is overwritten.
.RE
.RE
.PP
The function `tchdbputkeep' is used in order to store a new record into a hash database object.
.PP
.RS
.br
\fBbool tchdbputkeep(TCHDB *\fIhdb\fB, const void *\fIkbuf\fB, int \fIksiz\fB, const void *\fIvbuf\fB, int \fIvsiz\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkbuf\fR' specifies the pointer to the region of the key.
.RE
.RS
`\fIksiz\fR' specifies the size of the region of the key.
.RE
.RS
`\fIvbuf\fR' specifies the pointer to the region of the value.
.RE
.RS
`\fIvsiz\fR' specifies the size of the region of the value.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
If a record with the same key exists in the database, this function has no effect.
.RE
.RE
.PP
The function `tchdbputkeep2' is used in order to store a new string record into a hash database object.
.PP
.RS
.br
\fBbool tchdbputkeep2(TCHDB *\fIhdb\fB, const char *\fIkstr\fB, const char *\fIvstr\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkstr\fR' specifies the string of the key.
.RE
.RS
`\fIvstr\fR' specifies the string of the value.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
If a record with the same key exists in the database, this function has no effect.
.RE
.RE
.PP
The function `tchdbputcat' is used in order to concatenate a value at the end of the existing record in a hash database object.
.PP
.RS
.br
\fBbool tchdbputcat(TCHDB *\fIhdb\fB, const void *\fIkbuf\fB, int \fIksiz\fB, const void *\fIvbuf\fB, int \fIvsiz\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkbuf\fR' specifies the pointer to the region of the key.
.RE
.RS
`\fIksiz\fR' specifies the size of the region of the key.
.RE
.RS
`\fIvbuf\fR' specifies the pointer to the region of the value.
.RE
.RS
`\fIvsiz\fR' specifies the size of the region of the value.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
If there is no corresponding record, a new record is created.
.RE
.RE
.PP
The function `tchdbputcat2' is used in order to concatenate a string value at the end of the existing record in a hash database object.
.PP
.RS
.br
\fBbool tchdbputcat2(TCHDB *\fIhdb\fB, const char *\fIkstr\fB, const char *\fIvstr\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkstr\fR' specifies the string of the key.
.RE
.RS
`\fIvstr\fR' specifies the string of the value.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
If there is no corresponding record, a new record is created.
.RE
.RE
.PP
The function `tchdbputasync' is used in order to store a record into a hash database object in asynchronous fashion.
.PP
.RS
.br
\fBbool tchdbputasync(TCHDB *\fIhdb\fB, const void *\fIkbuf\fB, int \fIksiz\fB, const void *\fIvbuf\fB, int \fIvsiz\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkbuf\fR' specifies the pointer to the region of the key.
.RE
.RS
`\fIksiz\fR' specifies the size of the region of the key.
.RE
.RS
`\fIvbuf\fR' specifies the pointer to the region of the value.
.RE
.RS
`\fIvsiz\fR' specifies the size of the region of the value.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
If a record with the same key exists in the database, it is overwritten.  Records passed to this function are accumulated into the inner buffer and wrote into the file at a blast.
.RE
.RE
.PP
The function `tchdbputasync2' is used in order to store a string record into a hash database object in asynchronous fashion.
.PP
.RS
.br
\fBbool tchdbputasync2(TCHDB *\fIhdb\fB, const char *\fIkstr\fB, const char *\fIvstr\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkstr\fR' specifies the string of the key.
.RE
.RS
`\fIvstr\fR' specifies the string of the value.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RS
If a record with the same key exists in the database, it is overwritten.  Records passed to this function are accumulated into the inner buffer and wrote into the file at a blast.
.RE
.RE
.PP
The function `tchdbout' is used in order to remove a record of a hash database object.
.PP
.RS
.br
\fBbool tchdbout(TCHDB *\fIhdb\fB, const void *\fIkbuf\fB, int \fIksiz\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkbuf\fR' specifies the pointer to the region of the key.
.RE
.RS
`\fIksiz\fR' specifies the size of the region of the key.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RE
.PP
The function `tchdbout2' is used in order to remove a string record of a hash database object.
.PP
.RS
.br
\fBbool tchdbout2(TCHDB *\fIhdb\fB, const char *\fIkstr\fB);\fR
.RS
`\fIhdb\fR' specifies the hash database object connected as a writer.
.RE
.RS
`\fIkstr\fR' specifies the string of the key.
.RE
.RS
If successful, the return value is true, else, it is false.
.RE
.RE
.PP
The function `tchdbget' is used in order to retrieve a record in a hash database object.
.PP
.RS
.br