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author | markm <markm@FreeBSD.org> | 2002-05-14 16:06:50 +0000 |
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committer | markm <markm@FreeBSD.org> | 2002-05-14 16:06:50 +0000 |
commit | aeefd5b3e2766cf2adf46ab0d391c6290c566150 (patch) | |
tree | 1b2346a595f785988975c71a5f29de7e01b24cc4 /secure/lib/libcrypto/man/lhash.3 | |
parent | fa71779225949e4336753dba62bf930087152e61 (diff) | |
download | FreeBSD-src-aeefd5b3e2766cf2adf46ab0d391c6290c566150.zip FreeBSD-src-aeefd5b3e2766cf2adf46ab0d391c6290c566150.tar.gz |
As the perl-generated assembler files have been committed, add the
perl-generated (.pod) manual pages too. This is another nail in the
perl5 coffin (for base perl, not the port or the language in general).
Diffstat (limited to 'secure/lib/libcrypto/man/lhash.3')
-rw-r--r-- | secure/lib/libcrypto/man/lhash.3 | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/secure/lib/libcrypto/man/lhash.3 b/secure/lib/libcrypto/man/lhash.3 new file mode 100644 index 0000000..619e4d9 --- /dev/null +++ b/secure/lib/libcrypto/man/lhash.3 @@ -0,0 +1,292 @@ +.\" Automatically generated by Pod::Man version 1.15 +.\" Thu May 9 13:19:27 2002 +.\" +.\" Standard preamble: +.\" ====================================================================== +.de Sh \" Subsection heading +.br +.if t .Sp +.ne 5 +.PP +\fB\\$1\fR +.PP +.. +.de Sp \" Vertical space (when we can't use .PP) +.if t .sp .5v +.if n .sp +.. +.de Ip \" List item +.br +.ie \\n(.$>=3 .ne \\$3 +.el .ne 3 +.IP "\\$1" \\$2 +.. +.de Vb \" Begin verbatim text +.ft CW +.nf +.ne \\$1 +.. +.de Ve \" End verbatim text +.ft R + +.fi +.. +.\" Set up some character translations and predefined strings. \*(-- will +.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left +.\" double quote, and \*(R" will give a right double quote. | will give a +.\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used +.\" to do unbreakable dashes and therefore won't be available. \*(C` and +.\" \*(C' expand to `' in nroff, nothing in troff, for use with C<> +.tr \(*W-|\(bv\*(Tr +.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' +.ie n \{\ +. ds -- \(*W- +. ds PI pi +. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch +. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch +. ds L" "" +. ds R" "" +. ds C` "" +. ds C' "" +'br\} +.el\{\ +. ds -- \|\(em\| +. ds PI \(*p +. ds L" `` +. ds R" '' +'br\} +.\" +.\" If the F register is turned on, we'll generate index entries on stderr +.\" for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and +.\" index entries marked with X<> in POD. Of course, you'll have to process +.\" the output yourself in some meaningful fashion. +.if \nF \{\ +. de IX +. tm Index:\\$1\t\\n%\t"\\$2" +.. +. nr % 0 +. rr F +.\} +.\" +.\" For nroff, turn off justification. Always turn off hyphenation; it +.\" makes way too many mistakes in technical documents. +.hy 0 +.if n .na +.\" +.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). +.\" Fear. Run. Save yourself. No user-serviceable parts. +.bd B 3 +. \" fudge factors for nroff and troff +.if n \{\ +. ds #H 0 +. ds #V .8m +. ds #F .3m +. ds #[ \f1 +. ds #] \fP +.\} +.if t \{\ +. ds #H ((1u-(\\\\n(.fu%2u))*.13m) +. ds #V .6m +. ds #F 0 +. ds #[ \& +. ds #] \& +.\} +. \" simple accents for nroff and troff +.if n \{\ +. ds ' \& +. ds ` \& +. ds ^ \& +. ds , \& +. ds ~ ~ +. ds / +.\} +.if t \{\ +. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" +. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' +. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' +. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' +. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' +. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' +.\} +. \" troff and (daisy-wheel) nroff accents +.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' +.ds 8 \h'\*(#H'\(*b\h'-\*(#H' +.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] +.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' +.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' +.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] +.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] +.ds ae a\h'-(\w'a'u*4/10)'e +.ds Ae A\h'-(\w'A'u*4/10)'E +. \" corrections for vroff +.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' +.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' +. \" for low resolution devices (crt and lpr) +.if \n(.H>23 .if \n(.V>19 \ +\{\ +. ds : e +. ds 8 ss +. ds o a +. ds d- d\h'-1'\(ga +. ds D- D\h'-1'\(hy +. ds th \o'bp' +. ds Th \o'LP' +. ds ae ae +. ds Ae AE +.\} +.rm #[ #] #H #V #F C +.\" ====================================================================== +.\" +.IX Title "LHASH 1" +.TH LHASH 1 "perl v5.6.1" "2000-11-13" "User Contributed Perl Documentation" +.UC +.SH "NAME" +lh_new, lh_free, lh_insert, lh_delete, lh_retrieve, lh_doall, +lh_doall_arg, lh_error \- dynamic hash table +.SH "SYNOPSIS" +.IX Header "SYNOPSIS" +.Vb 1 +\& #include <openssl/lhash.h> +.Ve +.Vb 3 +\& LHASH *lh_new(unsigned long (*hash)(/*void *a*/), +\& int (*compare)(/*void *a,void *b*/)); +\& void lh_free(LHASH *table); +.Ve +.Vb 3 +\& void *lh_insert(LHASH *table, void *data); +\& void *lh_delete(LHASH *table, void *data); +\& void *lh_retrieve(LHASH *table, void *data); +.Ve +.Vb 3 +\& void lh_doall(LHASH *table, void (*func)(/*void *b*/)); +\& void lh_doall_arg(LHASH *table, void (*func)(/*void *a,void *b*/), +\& void *arg); +.Ve +.Vb 1 +\& int lh_error(LHASH *table); +.Ve +.SH "DESCRIPTION" +.IX Header "DESCRIPTION" +This library implements dynamic hash tables. The hash table entries +can be arbitrary structures. Usually they consist of key and value +fields. +.PP +\&\fIlh_new()\fR creates a new \fB\s-1LHASH\s0\fR structure. \fBhash\fR takes a pointer to +the structure and returns an unsigned long hash value of its key +field. The hash value is normally truncated to a power of 2, so make +sure that your hash function returns well mixed low order +bits. \fBcompare\fR takes two arguments, and returns 0 if their keys are +equal, non-zero otherwise. +.PP +\&\fIlh_free()\fR frees the \fB\s-1LHASH\s0\fR structure \fBtable\fR. Allocated hash table +entries will not be freed; consider using \fIlh_doall()\fR to deallocate any +remaining entries in the hash table. +.PP +\&\fIlh_insert()\fR inserts the structure pointed to by \fBdata\fR into \fBtable\fR. +If there already is an entry with the same key, the old value is +replaced. Note that \fIlh_insert()\fR stores pointers, the data are not +copied. +.PP +\&\fIlh_delete()\fR deletes an entry from \fBtable\fR. +.PP +\&\fIlh_retrieve()\fR looks up an entry in \fBtable\fR. Normally, \fBdata\fR is +a structure with the key \fIfield\fR\|(s) set; the function will return a +pointer to a fully populated structure. +.PP +\&\fIlh_doall()\fR will, for every entry in the hash table, call \fBfunc\fR with +the data item as parameters. +This function can be quite useful when used as follows: + void cleanup(\s-1STUFF\s0 *a) + { \fISTUFF_free\fR\|(a); } + lh_doall(hash,cleanup); + lh_free(hash); +This can be used to free all the entries. \fIlh_free()\fR then cleans up the +\&'buckets' that point to nothing. When doing this, be careful if you +delete entries from the hash table in \fBfunc\fR: the table may decrease +in size, moving item that you are currently on down lower in the hash +table. This could cause some entries to be skipped. The best +solution to this problem is to set hash->down_load=0 before you +start. This will stop the hash table ever being decreased in size. +.PP +\&\fIlh_doall_arg()\fR is the same as \fIlh_doall()\fR except that \fBfunc\fR will +be called with \fBarg\fR as the second argument. +.PP +\&\fIlh_error()\fR can be used to determine if an error occurred in the last +operation. \fIlh_error()\fR is a macro. +.SH "RETURN VALUES" +.IX Header "RETURN VALUES" +\&\fIlh_new()\fR returns \fB\s-1NULL\s0\fR on error, otherwise a pointer to the new +\&\fB\s-1LHASH\s0\fR structure. +.PP +When a hash table entry is replaced, \fIlh_insert()\fR returns the value +being replaced. \fB\s-1NULL\s0\fR is returned on normal operation and on error. +.PP +\&\fIlh_delete()\fR returns the entry being deleted. \fB\s-1NULL\s0\fR is returned if +there is no such value in the hash table. +.PP +\&\fIlh_retrieve()\fR returns the hash table entry if it has been found, +\&\fB\s-1NULL\s0\fR otherwise. +.PP +\&\fIlh_error()\fR returns 1 if an error occurred in the last operation, 0 +otherwise. +.PP +\&\fIlh_free()\fR, \fIlh_doall()\fR and \fIlh_doall_arg()\fR return no values. +.SH "BUGS" +.IX Header "BUGS" +\&\fIlh_insert()\fR returns \fB\s-1NULL\s0\fR both for success and error. +.SH "INTERNALS" +.IX Header "INTERNALS" +The following description is based on the SSLeay documentation: +.PP +The \fBlhash\fR library implements a hash table described in the +\&\fICommunications of the \s-1ACM\s0\fR in 1991. What makes this hash table +different is that as the table fills, the hash table is increased (or +decreased) in size via \fIOPENSSL_realloc()\fR. When a 'resize' is done, instead of +all hashes being redistributed over twice as many 'buckets', one +bucket is split. So when an 'expand' is done, there is only a minimal +cost to redistribute some values. Subsequent inserts will cause more +single 'bucket' redistributions but there will never be a sudden large +cost due to redistributing all the 'buckets'. +.PP +The state for a particular hash table is kept in the \fB\s-1LHASH\s0\fR structure. +The decision to increase or decrease the hash table size is made +depending on the 'load' of the hash table. The load is the number of +items in the hash table divided by the size of the hash table. The +default values are as follows. If (hash->up_load < load) => +expand. if (hash->down_load > load) => contract. The +\&\fBup_load\fR has a default value of 1 and \fBdown_load\fR has a default value +of 2. These numbers can be modified by the application by just +playing with the \fBup_load\fR and \fBdown_load\fR variables. The 'load' is +kept in a form which is multiplied by 256. So +hash->up_load=8*256; will cause a load of 8 to be set. +.PP +If you are interested in performance the field to watch is +num_comp_calls. The hash library keeps track of the 'hash' value for +each item so when a lookup is done, the 'hashes' are compared, if +there is a match, then a full compare is done, and +hash->num_comp_calls is incremented. If num_comp_calls is not equal +to num_delete plus num_retrieve it means that your hash function is +generating hashes that are the same for different values. It is +probably worth changing your hash function if this is the case because +even if your hash table has 10 items in a 'bucket', it can be searched +with 10 \fBunsigned long\fR compares and 10 linked list traverses. This +will be much less expensive that 10 calls to you compare function. +.PP +\&\fIlh_strhash()\fR is a demo string hashing function: +.PP +.Vb 1 +\& unsigned long lh_strhash(const char *c); +.Ve +Since the \fB\s-1LHASH\s0\fR routines would normally be passed structures, this +routine would not normally be passed to \fIlh_new()\fR, rather it would be +used in the function passed to \fIlh_new()\fR. +.SH "SEE ALSO" +.IX Header "SEE ALSO" +lh_stats(3) +.SH "HISTORY" +.IX Header "HISTORY" +The \fBlhash\fR library is available in all versions of SSLeay and OpenSSL. +\&\fIlh_error()\fR was added in SSLeay 0.9.1b. +.PP +This manpage is derived from the SSLeay documentation. |