NNAAMMEE DbMpool - shared memory buffer pool SSYYNNOOPPSSIISS ##iinncclluuddee <> ssttaattiicc iinntt DDbbMMppooooll::::ooppeenn((cchhaarr **ddiirr,, uu__iinntt3322__tt ffllaaggss,, iinntt mmooddee,, DDbbEEnnvv **ddbbeennvv,, DDbbMMppooooll ****rreeggiioonnpp));; iinntt DDbbMMppooooll::::cclloossee(());; ssttaattiicc iinntt DDbbMMppooooll::::uunnlliinnkk((ccoonnsstt cchhaarr **ddiirr,, iinntt ffoorrccee,, DDbbEEnnvv **));; iinntt DDbbMMppooooll::::ddbb__rreeggiisstteerr((iinntt ffttyyppee,, iinntt ((**ppggiinn))((ddbb__ppggnnoo__tt ppggnnoo,, vvooiidd **ppggaaddddrr,, DDbbtt **ppggccooookkiiee)),, iinntt ((**ppggoouutt))((ddbb__ppggnnoo__tt ppggnnoo,, vvooiidd **ppggaaddddrr,, DDbbtt **ppggccooookkiiee))));; iinntt DDbbMMppooooll::::ttrriicckkllee((iinntt ppcctt,, iinntt **nnwwrrootteepp));; iinntt DDbbMMppooooll::::ssyynncc((LLSSNN **llssnn));; iinntt DDbbMMppooooll::::ssttaatt((DDBB__MMPPOOOOLL__SSTTAATT ****ggsspp,, DDBB__MMPPOOOOLL__FFSSTTAATT **((**ffsspp))[[]],, vvooiidd **((**ddbb__mmaalllloocc))((ssiizzee__tt))));; DDEESSCCRRIIPPTTIIOONN The DB library is a family of classes that provides a mod- ular programming interface to transactions and record-ori- ented file access. The library includes support for transactions, locking, logging and file page caching, as well as various indexed access methods. Many of the classes (e.g., the file page caching class) are useful independent of the other DB classes, although some classes are explicitly based on other classes (e.g., transactions and logging). For a general description of the DB pack- age, see _d_b___i_n_t_r_o(3). This manual page describes the specific details of the memory pool interface. The _D_b_M_p_o_o_l(3) and _D_b_M_p_o_o_l_F_i_l_e(3) classes are the library interface intended to provide general-purpose, page-ori- ented buffer management of one or more files. While designed to work with the other Db classes, this class is also useful for more general purposes. The memory pools (DbMpool's) are referred to in this document as simply ``pools''. Pools may be shared between processes. Pools are usually filled by pages from one or more files (DbM- poolFile's). Pages in the pool are replaced in LRU (least-recently-used) order, with each new page replacing the page that has been unused the longest. Pages retrieved from the pool using _D_b_M_p_o_o_l_F_i_l_e_:_:_g_e_t are ``pinned'' in the pool, by default, until they are returned to the pool's control using the _D_b_M_p_o_o_l_F_i_l_e_:_:_p_u_t method. _D_b_M_p_o_o_l_:_:_o_p_e_n The _D_b_M_p_o_o_l_:_:_o_p_e_n method copies a pointer, to the memory pool identified by the ddiirreeccttoorryy _d_i_r, into the memory location referenced by _r_e_g_i_o_n_p. If the _d_b_e_n_v argument to _D_b_M_p_o_o_l_:_:_o_p_e_n was initialized using _D_b_E_n_v_:_:_a_p_p_i_n_i_t, _d_i_r is interpreted as described by _D_b_E_n_v(3). Otherwise, if _d_i_r is not NULL, it is interpreted relative to the current working directory of the process. If _d_i_r is NULL, the following environment variables are checked in order: ``TMPDIR'', ``TEMP'', and ``TMP''. If one of them is set, memory pool files are created relative to the directory it specifies. If none of them are set, the first possible one of the following directories is used: _/_v_a_r_/_t_m_p, _/_u_s_r_/_t_m_p, _/_t_e_m_p, _/_t_m_p, _C_:_/_t_e_m_p and _C_:_/_t_m_p. All files associated with the memory pool are created in this directory. This directory must already exist when DbMpool::open is called. If the memory pool already exists, the process must have permission to read and write the existing files. If the memory pool does not already exist, it is optionally created and initialized. The _f_l_a_g_s and _m_o_d_e arguments specify how files will be opened and/or created when they don't already exist. The flags value is specified by oorr'ing together one or more of the following values: DB_CREATE Create any underlying files, as necessary. If the files do not already exist and the DB_CREATE flag is not specified, the call will fail. DB_MPOOL_PRIVATE Create a private MPOOL that is not shared with any other process (although it may be shared with other threads). DB_NOMMAP Always copy files in this memory pool into the local cache instead of mapping them into process memory (see the description of the _m_p___m_m_a_p_s_i_z_e field of the DbEnv object for further information). DB_THREAD Cause the DbMpool handle returned by the _D_b_M_- _p_o_o_l_:_:_o_p_e_n method to be useable by multiple threads within a single address space, i.e., to be ``free- threaded''. All files created by the memory pool subsystem (other than files created by the _m_e_m_p___f_o_p_e_n method, which are sepa- rately specified) are created with mode _m_o_d_e (as described in _c_h_m_o_d(2)) and modified by the process' umask value at the time of creation (see _u_m_a_s_k(2)). The group ownership of created files is based on the system and directory defaults, and is not further specified by DB. The memory pool subsystem is configured based on which set methods have been used. It is expected that applications will use a single DbEnv object as the argument to all of the subsystems in the DB package. The fields of the DbEnv object used by _D_b_M_p_o_o_l_:_:_o_p_e_n are described below. As ref- erences to the DbEnv object may be maintained by _D_b_M_- _p_o_o_l_:_:_o_p_e_n, it is necessary that the DbEnv object and mem- ory it references be valid until the object is destroyed. Any of the DbEnv fields that are not explicitly set will default to appropriate values. The following fields in the DbEnv object may be initial- ized, using the appropriate set method, before calling _D_b_M_p_o_o_l_:_:_o_p_e_n: void *(*db_errcall)(char *db_errpfx, char *buffer); FILE *db_errfile; const char *db_errpfx; class ostream *db_error_stream; int db_verbose; The error fields of the DbEnv behave as described for _D_b_E_n_v(3). size_t mp_mmapsize; Files that are opened read-only in the pool (and that satisfy a few other criteria) are, by default, mapped into the process address space instead of being copied into the local cache. This can result in bet- ter-than-usual performance, as available virtual mem- ory is normally much larger than the local cache, and page faults are faster than page copying on many sys- tems. However, in the presence of limited virtual memory it can cause resource starvation, and in the presence of large databases, it can result in immense process sizes. If _m_p___m_m_a_p_s_i_z_e is non-zero, it speci- fies the maximum file size, in bytes, for a file to be mapped into the process address space. By default, it is set to 10Mb. size_t mp_size; The suggested size of the pool, in bytes. This should be the size of the normal working data set of the application, with some small amount of additional memory for unusual situations. (Note, the working set is not the same as the number of simultaneously referenced pages, and should be quite a bit larger!) The default cache size is 128K bytes (16 8K byte pages), and may not be less than 20K bytes. The _D_b_M_p_o_o_l_:_:_o_p_e_n method throws a _D_b_E_x_c_e_p_t_i_o_n(3) or returns the value of _e_r_r_n_o on failure and 0 on success. _D_b_M_p_o_o_l_:_:_c_l_o_s_e The _D_b_M_p_o_o_l_:_:_c_l_o_s_e method closes the pool indicated by the DbMpool object, as returned by _D_b_M_p_o_o_l_:_:_o_p_e_n. This method does not imply a call to _D_b_M_p_o_o_l_F_i_l_e_:_:_s_y_n_c, but does imply a call to _D_b_M_p_o_o_l_F_i_l_e_:_:_c_l_o_s_e for any remaining open DbM- poolFile objects returned to this process by calls to _D_b_M_- _p_o_o_l_F_i_l_e_:_:_o_p_e_n. In addition, if the _d_i_r argument to _D_b_M_p_o_o_l_:_:_o_p_e_n was NULL and _d_b_e_n_v was not initialized using _D_b_E_n_v_:_:_a_p_p_i_n_i_t, all files created for this shared region will be removed, as if _D_b_M_p_o_o_l_:_:_u_n_l_i_n_k were called. When multiple threads are using the DbMpool handle concur- rently, only a single thread may call the _D_b_M_p_o_o_l_:_:_c_l_o_s_e method. The _D_b_M_p_o_o_l_:_:_c_l_o_s_e method throws a _D_b_E_x_c_e_p_t_i_o_n(3) or returns the value of _e_r_r_n_o on failure and 0 on success. _D_b_M_p_o_o_l_:_:_u_n_l_i_n_k The _D_b_M_p_o_o_l_:_:_u_n_l_i_n_k method destroys the memory pool iden- tified by the directory _d_i_r, removing all files used to implement the memory pool. (The directory _d_i_r is not removed.) If there are processes that have called _D_b_M_- _p_o_o_l_:_:_o_p_e_n without calling _D_b_M_p_o_o_l_:_:_c_l_o_s_e (i.e., there are processes currently using the memory pool), _D_b_M_- _p_o_o_l_:_:_u_n_l_i_n_k will fail without further action, unless the force flag is set, in which case _D_b_M_p_o_o_l_:_:_u_n_l_i_n_k will attempt to remove the memory pool files regardless of any processes still using the memory pool. The result of attempting to forcibly destroy the region when a process has the region open is unspecified. Pro- cesses using a shared memory region maintain an open file descriptor for it. On UNIX systems, the region removal should succeed and processes that have already joined the region should continue to run in the region without change, however processes attempting to join the memory pool will either fail or attempt to create a new region. On other systems, e.g., WNT, where the _u_n_l_i_n_k(2) system call will fail if any process has an open file descriptor for the file, the region removal will fail. In the case of catastrophic or system failure, database recovery must be performed (see _d_b___r_e_c_o_v_e_r(1) or the DB_RECOVER and DB_RECOVER_FATAL flags to _D_b_E_n_v_:_:_a_p_p_i_n_i_t(3)). Alternatively, if recovery is not required because no database state is maintained across failures, it is possible to clean up a memory pool by removing all of the files in the directory specified to the _D_b_M_p_o_o_l_:_:_o_p_e_n method, as memory pool files are never created in any directory other than the one specified to _D_b_M_p_o_o_l_:_:_o_p_e_n. Note, however, that this has the potential to remove files created by the other DB subsystems in this database environment. The _D_b_M_p_o_o_l_:_:_u_n_l_i_n_k method throws a _D_b_E_x_c_e_p_t_i_o_n(3) or returns the value of _e_r_r_n_o on failure and 0 on success. _D_b_M_p_o_o_l_:_:_d_b___r_e_g_i_s_t_e_r The _D_b_M_p_o_o_l_:_:_d_b___r_e_g_i_s_t_e_r method registers page-in and page-out functions for files of type _f_t_y_p_e in the speci- fied pool. If the _p_g_i_n function is non-NULL, it is called each time a page is read into the memory pool from a file of type _f_t_y_p_e, or a page is created for a file of type _f_t_y_p_e (see the DB_MPOOL_CREATE flag for the _D_b_M_p_o_o_l_F_i_l_e_:_:_g_e_t method). If the _p_g_o_u_t function is non-NULL, it is called each time a page is written to a file of type _f_t_y_p_e. Both the _p_g_i_n and _p_g_o_u_t functions are called with the page number, a pointer to the page being read or written, and any argument _p_g_c_o_o_k_i_e that was specified to the _D_b_M_- _p_o_o_l_F_i_l_e_:_:_o_p_e_n method when the file was opened. The _p_g_i_n and _p_g_o_u_t functions should return 0 on success, and an applicable non-zero _e_r_r_n_o value on failure, in which case the _D_b_M_p_o_o_l method calling it will also fail, returning that _e_r_r_n_o value. The purpose of the _D_b_M_p_o_o_l_:_:_d_b___r_e_g_i_s_t_e_r method is to sup- port processing when pages are entered into, or flushed from, the pool. A file type must be specified to make it possible for unrelated threads or processes, that are sharing a pool, to evict each other's pages from the pool. Applications should call _D_b_M_p_o_o_l_:_:_d_b___r_e_g_i_s_t_e_r, during ini- tialization, for each type of file requiring input or out- put processing that will be sharing the underlying pool. (No registry is necessary for the standard access method types, btree, hash and recno, as _D_b_:_:_o_p_e_n(3) registers them separately.) If a thread or process does not call _D_b_M_p_o_o_l_:_:_d_b___r_e_g_i_s_t_e_r for a file type, it is impossible for it to evict pages for any file requiring input or output processing from the pool. For this reason, _D_b_M_p_o_o_l_:_:_d_b___r_e_g_i_s_t_e_r should always be called by each application sharing a pool for each type of file included in the pool, regardless of whether or not the application itself uses files of that type. There are no standard values for _f_t_y_p_e, _p_g_i_n, _p_g_o_u_t and _p_g_c_o_o_k_i_e, except that the _f_t_y_p_e value for a file must be a non-zero positive number, as negative numbers are reserved for internal use by the DB library. For this reason, applications sharing a pool must coordinate their values amongst themselves. The _D_b_M_p_o_o_l_:_:_d_b___r_e_g_i_s_t_e_r method throws a _D_b_E_x_c_e_p_t_i_o_n(3) or returns the value of _e_r_r_n_o on failure and 0 on success. _D_b_M_p_o_o_l_:_:_t_r_i_c_k_l_e The _D_b_M_p_o_o_l_:_:_t_r_i_c_k_l_e method ensures that at least _p_c_t per- cent of the pages in the shared memory pool are clean by writing dirty pages to their backing files. If the _n_w_r_o_t_e_p argument is non-NULL, the number of pages that were written to reach the correct percentage is returned in the memory location it references. The purpose of the _D_b_M_p_o_o_l_:_:_t_r_i_c_k_l_e method is to enable a memory pool manager to ensure that a page is always avail- able for reading in new information without having to wait for a write. The _D_b_M_p_o_o_l_:_:_t_r_i_c_k_l_e method throws a _D_b_E_x_c_e_p_t_i_o_n(3) or returns the value of _e_r_r_n_o on failure and 0 on success. _D_b_M_p_o_o_l_:_:_s_y_n_c The _D_b_M_p_o_o_l_:_:_s_y_n_c method ensures that all the modified pages in the pool with log sequence numbers (LSNs) less than the _l_s_n argument are written to disk. The _D_b_M_p_o_o_l_:_:_s_y_n_c method throws a _D_b_E_x_c_e_p_t_i_o_n(3) or returns the value of _e_r_r_n_o on failure, 0 on success, and DB_INCOMPLETE if there were pages which need to be written but which _D_b_M_p_o_o_l_:_:_s_y_n_c was unable to write immediately. In addition, if _D_b_M_p_o_o_l_:_:_s_y_n_c returns success, the value of _l_s_n will be overwritten with the largest LSN from any page which was written by _D_b_M_p_o_o_l_:_:_s_y_n_c to satisfy this request. The purpose of the _D_b_M_p_o_o_l_:_:_s_y_n_c method is to enable a transaction manager to ensure, as part of a checkpoint, that all pages modified by a certain time have been writ- ten to disk. Pages in the pool which cannot be written back to disk immediately (e.g., are currently pinned) are written to disk as soon as it is possible to do so. The expected behavior of the transaction manager is to call the _D_b_M_p_o_o_l_:_:_s_y_n_c method and then, if the return indicates that some pages could not be written immediately, to wait briefly and retry again with the same LSN until the _D_b_M_- _p_o_o_l_:_:_s_y_n_c method returns that all pages have been written. To support the _D_b_M_p_o_o_l_:_:_s_y_n_c functionality, it is neces- sary that the pool methods know the location of the LSN on the page for each file type. This location should be specified when the file is opened using the _D_b_M_- _p_o_o_l_F_i_l_e_:_:_o_p_e_n method. (Note, it is not required that the LSN be aligned on the page in any way.) _D_b_M_p_o_o_l_:_:_s_t_a_t The _D_b_M_p_o_o_l_:_:_s_t_a_t method creates statistical structures and copies pointers to them into user-specified memory locations. The statistics include the number of files participating in the pool, the active pages in the pool, and information as to how effective the cache has been. Statistical structures are created in allocated memory. If _d_b___m_a_l_l_o_c is non-NULL, it is called to allocate the memory, otherwise, the library function _m_a_l_l_o_c(3) is used. The function _d_b___m_a_l_l_o_c must match the calling conventions of the _m_a_l_l_o_c(3) library routine. Regardless, the caller is responsible for deallocating the returned memory. To deallocate the returned memory, free each returned memory pointer; pointers inside the memory do not need to be individually freed. If _g_s_p is non-NULL, the global statistics for the memory pool object are copied into the memory location it refer- ences. The global statistics are stored in a structure of type DB_MPOOL_STAT (typedef'd in ). The following DB_MPOOL_STAT fields will be filled in: u_int32_t st_refcnt; The number of references to the region. u_int32_t st_regsize; The size of the region. size_t st_cachesize; Cache size in bytes. u_int32_t st_cache_hit; Requested pages found in the cache. u_int32_t st_cache_miss; Requested pages not found in the cache. u_int32_t st_map; Requested pages mapped into the process' address space (there is no available information as to whether or not this request caused disk I/O, although examining the application page fault rate may be helpful). u_int32_t st_page_create; Pages created in the cache. u_int32_t st_page_in; Pages read into the cache. u_int32_t st_page_out; Pages written from the cache to the backing file. u_int32_t st_ro_evict; Clean pages forced from the cache. u_int32_t st_rw_evict; Dirty pages forced from the cache. u_int32_t st_hash_buckets; Number of hash buckets in buffer hash table. u_int32_t st_hash_searches; Total number of buffer hash table lookups. u_int32_t st_hash_longest; The longest chain ever encountered in buffer hash table lookups. u_int32_t st_hash_examined; Total number of hash elements traversed during hash table lookups. u_int32_t st_page_clean; Clean pages currently in the cache. u_int32_t st_page_dirty; Dirty pages currently in the cache. u_int32_t st_page_trickle; Dirty pages written using the _m_e_m_p___t_r_i_c_k_l_e interface. If _f_s_p is non-NULL, a pointer to a NULL-terminated vari- able length array of statistics for individual files in the memory pool is copied into the memory location it ref- erences. If no individual files currently exist in the memory pool, _f_s_p will be set to NULL. The per-file statistics are stored in structures of type DB_MPOOL_FSTAT (typedef'd in ). The following DB_MPOOL_FSTAT fields will be filled in for each file in the pool, i.e., each element of the array: char *file_name; The name of the file. size_t st_pagesize; Page size in bytes. u_int32_t st_cache_hit; Requested pages found in the cache. u_int32_t st_cache_miss; Requested pages not found in the cache. u_int32_t st_map; Requested pages mapped into the process' address space. u_int32_t st_page_create; Pages created in the cache. u_int32_t st_page_in; Pages read into the cache. u_int32_t st_page_out; Pages written from the cache to the backing file. The _D_b_M_p_o_o_l_:_:_s_t_a_t method throws a _D_b_E_x_c_e_p_t_i_o_n(3) or returns the value of _e_r_r_n_o on failure and 0 on success. EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS The following environment variables affect the behavior of _D_b_M_p_o_o_l_F_i_l_e: DB_HOME If the _d_b_e_n_v argument to _D_b_M_p_o_o_l_:_:_o_p_e_n was initial- ized using _d_b___a_p_p_i_n_i_t, the environment variable DB_HOME may be used as the path of the database home for the interpretation of the _d_i_r argument to _D_b_M_- _p_o_o_l_:_:_o_p_e_n, as described in _d_b___a_p_p_i_n_i_t(3). TMPDIR If the _d_b_e_n_v argument to _D_b_M_p_o_o_l_:_:_o_p_e_n was NULL or not initialized using _d_b___a_p_p_i_n_i_t, the environment variable TMPDIR may be used as the directory in which to create the memory pool, as described in the _D_b_M_- _p_o_o_l_:_:_o_p_e_n section above. EERRRROORRSS Methods marked as returning _e_r_r_n_o will, by default, throw an exception that encapsulates the error information. The default error behavior can be changed, see _D_b_E_x_c_e_p_t_i_o_n(3). The _D_b_M_p_o_o_l_:_:_o_p_e_n method may fail and throw a _D_b_E_x_c_e_p_- _t_i_o_n(3) or return _e_r_r_n_o for any of the errors specified for the following DB and library functions: DBmemp->pgin(3), DBmemp->pgout(3), DbLog::compare(3), DbLog::flush(3), DbM- pool::close(3), DbMpool::unlink(3), close(2), db_ver- sion(3), fcntl(2), fflush(3), fsync(2), lseek(2), mal- loc(3), memcmp(3), memcpy(3), memset(3), mmap(2), mun- map(2), open(2), sigfillset(3), sigprocmask(2), stat(2), strcpy(3), strdup(3), strerror(3), strlen(3), time(3), unlink(2), and write(2). In addition, the _D_b_M_p_o_o_l_:_:_o_p_e_n method may fail and throw a _D_b_E_x_c_e_p_t_i_o_n(3) or return _e_r_r_n_o for the following condi- tions: [EAGAIN] The shared memory region was locked and (repeatedly) unavailable. [EINVAL] An invalid flag value or parameter was specified. The DB_THREAD flag was specified and spinlocks are not implemented for this architecture. A NULL pathname was specified without the DB_MPOOL_PRIVATE flag. The specified cache size was impossibly small. The _D_b_M_p_o_o_l_:_:_c_l_o_s_e method may fail and throw a _D_b_E_x_c_e_p_- _t_i_o_n(3) or return _e_r_r_n_o for any of the errors specified for the following DB and library functions: DbMpoolFile::close(3), close(2), fcntl(2), fflush(3), munmap(2), and strerror(3). The _D_b_M_p_o_o_l_:_:_u_n_l_i_n_k method may fail and throw a _D_b_E_x_c_e_p_- _t_i_o_n(3) or return _e_r_r_n_o for any of the errors specified for the following DB and library functions: close(2), fcntl(2), fflush(3), malloc(3), memcpy(3), memset(3), mmap(2), mun- map(2), open(2), sigfillset(3), sigprocmask(2), stat(2), strcpy(3), strdup(3), strerror(3), strlen(3), and unlink(2). In addition, the _D_b_M_p_o_o_l_:_:_u_n_l_i_n_k method may fail and throw a _D_b_E_x_c_e_p_t_i_o_n(3) or return _e_r_r_n_o for the following condi- tions: [EBUSY] The shared memory region was in use and the force flag was not set. The _D_b_M_p_o_o_l_:_:_d_b___r_e_g_i_s_t_e_r method may fail and throw a _D_b_E_x_- _c_e_p_t_i_o_n(3) or return _e_r_r_n_o for any of the errors specified for the following DB and library functions: fcntl(2), and mal- loc(3). The _D_b_M_p_o_o_l_:_:_t_r_i_c_k_l_e method may fail and throw a _D_b_E_x_c_e_p_- _t_i_o_n(3) or return _e_r_r_n_o for any of the errors specified for the following DB and library functions: DBmemp->pgin(3), DBmemp->pgout(3), DbLog::compare(3), DbLog::flush(3), close(2), fcntl(2), fflush(3), fsync(2), lseek(2), mal- loc(3), memcmp(3), memcpy(3), memset(3), mmap(2), open(2), sigfillset(3), sigprocmask(2), stat(2), strcpy(3), strdup(3), strerror(3), strlen(3), time(3), unlink(2), and write(2). In addition, the _D_b_M_p_o_o_l_:_:_t_r_i_c_k_l_e method may fail and throw a _D_b_E_x_c_e_p_t_i_o_n(3) or return _e_r_r_n_o for the following conditions: [EINVAL] An invalid flag value or parameter was specified. The _D_b_M_p_o_o_l_:_:_s_y_n_c method may fail and throw a _D_b_E_x_c_e_p_- _t_i_o_n(3) or return _e_r_r_n_o for any of the errors specified for the following DB and library functions: DBmemp->pgin(3), DBmemp->pgout(3), DbLog::compare(3), DbLog::flush(3), close(2), fcntl(2), fflush(3), fsync(2), lseek(2), mal- loc(3), memcmp(3), memcpy(3), memset(3), mmap(2), open(2), qsort(3), realloc(3), sigfillset(3), sigprocmask(2), stat(2), strcpy(3), strdup(3), strerror(3), strlen(3), time(3), unlink(2), and write(2). In addition, the _D_b_M_p_o_o_l_:_:_s_y_n_c method may fail and throw a _D_b_E_x_c_e_p_t_i_o_n(3) or return _e_r_r_n_o for the following condi- tions: [EINVAL] An invalid flag value or parameter was specified. The _D_b_M_p_o_o_l_:_:_s_y_n_c method was called without logging having been initialized in the environment. The _D_b_M_p_o_o_l_:_:_s_t_a_t method may fail and throw a _D_b_E_x_c_e_p_- _t_i_o_n(3) or return _e_r_r_n_o for any of the errors specified for the following DB and library functions: fcntl(2), malloc(3), memcpy(3), and strlen(3). SSEEEE AALLSSOO _d_b___a_r_c_h_i_v_e(1), _d_b___c_h_e_c_k_p_o_i_n_t(1), _d_b___d_e_a_d_l_o_c_k(1), _d_b___d_u_m_p(1), _d_b___l_o_a_d(1), _d_b___r_e_c_o_v_e_r(1), _d_b___s_t_a_t(1), _d_b___i_n_t_r_o(3), _d_b___i_n_t_e_r_n_a_l(3), _d_b___t_h_r_e_a_d(3), _D_b(3), _D_b_c(3), _D_b_E_n_v(3), _D_b_E_x_c_e_p_t_i_o_n(3), _D_b_I_n_f_o(3), _D_b_L_o_c_k(3), _D_b_L_o_c_k_T_a_b(3), _D_b_L_o_g(3), _D_b_L_s_n(3), _D_b_M_p_o_o_l(3), _D_b_M_p_o_o_l_F_i_l_e(3), _D_b_t(3), _D_b_T_x_n(3), _D_b_T_x_n_M_g_r(3)