Re: SQLite3 API support

[Hideki IWAMOTO]

Hi. Yamaguchi san.

Some misuse of sqlite pragma had caused the frequent system call.
After correcting them, use of the system call in execution of gtags became 
almost the same as the case of BerkeleyDB. 


Comparison using linux-2.0.40 source:

== 2014-11-11 version

$ strace -c -f -F -q -S calls gtags --sqlite3
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 35.59    9.569516          19    509832           ftruncate
 10.47    2.815148          10    287004         2 lseek
 14.43    3.880148          14    281053           write
 10.30    2.770895          11    258145           fstat
 12.02    3.231004          13    256977           mmap
 13.69    3.680895          14    256960           munmap
  2.71    0.727573          70     10386           read
  0.21    0.056610          11      5308         2 stat
  0.07    0.018480           6      3189           fcntl
  0.11    0.028525          11      2584        52 open
  0.07    0.018668           7      2540           close
  0.03    0.008301          12       686       677 access
  0.02    0.005682           9       638           lstat
  0.03    0.006742          17       388           brk
  0.20    0.052701         155       341           fsync
  0.02    0.004449          17       264           getdents64
  0.01    0.001693           6       263           getcwd
  0.00    0.000694          24        29         9 unlink
  0.00    0.000040           3        12           getrusage
  0.00    0.000068           8         9           mprotect
  0.01    0.003996        1332         3           truncate
  0.00    0.000009           3         3           geteuid
  0.00    0.000027          14         2           pipe
  0.00    0.000008           4         2           dup2
  0.00    0.000007           4         2           getpid
  0.03    0.007984        3992         2           execve
  0.00    0.000007           4         2           uname
  0.00    0.000006           3         2           arch_prctl
  0.00    0.000251         251         1           clone
  0.00    0.000168         168         1           wait4
------ ----------- ----------- --------- --------- ----------------
100.00   26.890295               1876628       742 total

== Current CVS head

$ strace -c -f -F -q -S calls gtags --sqlite3
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 26.15    0.114054          11     10386           read
  7.90    0.034441           4      9549         2 lseek
  9.48    0.041371           8      5300         2 stat
 22.60    0.098566          27      3598           write
  2.92    0.012742           4      3209           fstat
  3.87    0.016889           5      3173           fcntl
  5.28    0.023010           9      2576        52 open
  3.09    0.013474           5      2532           close
  3.12    0.013607           7      2060           mmap
  5.37    0.023433          11      2043           munmap
  1.53    0.006693          10       670       669 access
  1.21    0.005273           8       638           lstat
  0.98    0.004279          16       264           getdents64
  0.47    0.002040           8       263           getcwd
  0.62    0.002690          13       209           brk
  0.11    0.000461          22        21         9 unlink
  0.03    0.000118           6        19           mremap
  2.48    0.010833         903        12           fsync
  0.01    0.000043           4        12           getrusage
  0.02    0.000068           8         9           mprotect
  2.48    0.010797        3599         3           truncate
  0.00    0.000010           3         3           geteuid
  0.01    0.000022          11         2           pipe
  0.00    0.000007           4         2           dup2
  0.00    0.000007           4         2           getpid
  0.15    0.000641         321         2           execve
  0.00    0.000006           3         2           uname
  0.00    0.000006           3         2           arch_prctl
  0.06    0.000240         240         1           clone
  0.08    0.000369         369         1           wait4
------ ----------- ----------- --------- --------- ----------------
100.00    0.436190                 46563       734 total
-- 
Hideki IWAMOTO <address@hidden>