1.5.97 first impression

[Richard Braakman]

On Sun, Jun 03, 2001 at 11:57:22PM -0700, Dave Peticolas wrote:
> On 03 Jun 2001 23:55:49 -0700, Jeffrey W. Baker wrote:
> > Right.  It is blocking on opening and reading /dev/random.  Perhaps an
> > upgrade to Guile 1.4 will fix that.
> 
> Strange. This is guile reading from /dev/random?

I traced it down to guppi (version 0.35.5).  In src/libguppiuseful,
file guppi-unique-id.c, there are several problems:

1. init_unique_id() reads from /dev/random to seed the random number generator.
I can't find any good reason for this -- surely /dev/urandom would be
good enough.  Its fallback based on time and getpid is worse than /dev/urandom
would be.

2. guppi_unique_id() calls init_unique_id() if "initialized" is false,
but it doesn't declare "initialized" as static.  This makes it call
init_unique_id() for every id.  (This probably makes the ids non-unique
as well.)

There are two problems which make the first worse.  They'll probably
not be relevant if /dev/urandom is used instead:

1a. init_unique_id() tries to read sizeof(unsigned) bytes from /dev/random,
but if it gets less than that, it ignores what it got.  This is wasteful.

1b. init_unique_id() has a fallback for /dev/random, but since it opens
/dev/random in blocking mode, it won't use the fallback until after it
gets at least one byte.  This could take a while.

I haven't checked if there's a guppi version that fixes these problems.
If there isn't, I hope that this is enough information to fix it :-)

Richard Braakman