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| 13 | .. |
| 14 | .TH dspool 3mLib "20 June 1999" mLib |
| 15 | .SH NAME |
| 16 | dspool \- pools of preallocated dynamic strings |
| 17 | .SH SYNOPSIS |
| 18 | .nf |
| 19 | .B "#include <mLib/dspool.h> |
| 20 | |
| 21 | .BI "void dspool_create(dspool *" p ", size_t " isz ); |
| 22 | .BI "void dspool_destroy(dspool *" p ); |
| 23 | .BI "dstr *dspool_get(dspool *" p ); |
| 24 | .BI "void dspool_put(dspool *" p ", dstr *" d ); |
| 25 | |
| 26 | .BI "dstr *DSGET(dspool *" p ", d ); |
| 27 | .BI "void DSPUT(dspool *" p ", dstr *" d ); |
| 28 | .fi |
| 29 | .SH DESCRIPTION |
| 30 | A dynamic string pool maintains a collection of `spare' dynamic |
| 31 | strings. Some pieces of code require high turnover of strings, and |
| 32 | allocating and freeing them entails a large amount of overhead. A |
| 33 | dynamic string pool keeps a list of dynamic strings which have been |
| 34 | allocated but are not currently in use. |
| 35 | .PP |
| 36 | A pool is created by the function |
| 37 | .BR dspool_create . |
| 38 | It is passed the address of a pool structure |
| 39 | .I p |
| 40 | and the initial size |
| 41 | .I izs |
| 42 | to allocate for new dynamic strings obtained from the pool. A newly |
| 43 | created pool contains no strings. Once a pool is no longer required, |
| 44 | the function |
| 45 | .B dspool_destroy |
| 46 | will release all the strings in the pool, such that the pool can safely |
| 47 | be thrown away. |
| 48 | .PP |
| 49 | A string is obtained from a pool by calling |
| 50 | .BR dspool_get . |
| 51 | If the pool is empty, a new string is allocated; otherwise a string is |
| 52 | chosen from those currently in the pool. |
| 53 | .PP |
| 54 | A string is returned to the pool by the |
| 55 | .B dspool_put |
| 56 | function. It is passed the address of a pool and the address of a |
| 57 | string to return. The string must have been allocated from |
| 58 | .I some |
| 59 | dynamic string pool, although it's not actually necessary to return it |
| 60 | to the pool from which it was allocated. |
| 61 | .PP |
| 62 | The macro call |
| 63 | .VS |
| 64 | DSGET(p, d); |
| 65 | .VE |
| 66 | is equivalent to the assignment |
| 67 | .VS |
| 68 | d = dspool_get(p); |
| 69 | .VE |
| 70 | (except that it's probably quicker). The macro |
| 71 | .B DSPUT |
| 72 | is entirely equivalent to the function |
| 73 | .B dspool_put |
| 74 | except for improved performance. |
| 75 | .SH CAVEATS |
| 76 | The string pool allocator requires the suballocator (see |
| 77 | .BR sub (3mLib) |
| 78 | for details). You must ensure that |
| 79 | .B sub_init |
| 80 | is called before any strings are allocated from a string pool. |
| 81 | .SH SEE ALSO |
| 82 | .BR dstr (3mLib), |
| 83 | .BR sub (3mLib). |
| 84 | .SH AUTHOR |
| 85 | Mark Wooding, <mdw@nsict.org> |
~mdw / mLib / blame