CS476/576

Assignment #3

Due Midnight, Wednesday   Nov 7, 2007

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Write a C/UNIX program with the following descriptions:

NAME

dispatch  -   Parent dispatches work among children.

SYNOPSIS

dispatch <n> <m> <InputFile> <OutputFile>

DESCRIPTION

The parent creates n (n<= 10) children processes.

Each process i is connected to the parent with PIPE_i and is assigned a unique signal SIG_i to send to its parent (do not assign SIGKILL!).

Child Process Activities:

Each process  i, i= 1, 2,.., n do the following:

Ø Logs a NEW record immediately after its creation in file ChildrenLog in the form:

NEW: i:PID (e.g., NEW:1:24171 )

Ø Sleeps a random amount of time T seconds (T <=5* n) and when it wakes up it perform the following actions:

1. Sends SIG_i to its parent.

2. Reads a block of 128 bytes from the PIPE_i

3. Saves the Read data in <OutputFile>.

4. Logs a Read record in file ChildrenLog in the form:

Read:i:PID:read# (e.g., Read:1:24171:4 )

5. Terminates after reading a total of m reads.

Ø Each child process Logs a DEAD record before its termination in file ChildrenLog in the form: DEAD:i:PID (e.g., DEAD:1:24171 )

Parent Process Activities:

The parent process performs the following actions:

Ø When it creates a new child i it Logs a NEW record in file ParentLog in the form: NEW:i:PID (e.g. NEW:1:24171 )

Ø When it gets SIG_i it reads a block of 128 bytes from <InputFile> , writes it to PIPE_i and Logs a SIG record in file ParentLog in the form:

SIG: i:PID (e.g. SIG:1:24171 )

Ø When child i terminates and there is more data to read from the <InputFile>, the parent creates another child process to replace i and Logs a REPL record in file ParentLog in the form:

REPL: i:PID (e.g. REPL:1:24175 )

Ø When a child i terminates, it Logs a DEAD record in file ParentLog in the form: DEAD: i:PID (e.g. DEAD:1:24171 )

Ø When there are no more data to read from <InputFile>, the program terminates.

The following figure is a general overview of the system:

Please see Dr. wahab’s solution is at:

http://www.cs.odu.edu/~cs476/fall07/assignments/a3/wahab/dispatch

You may use the shell script: check_sh to verify the accuracy of the results.

Examples: they all use InputFile

% dispatch 1 10 InputFile OutputFile

Results:

ChildrenLog_1_10

Prent_Log_1_10

check_1_10

% dispatch 10 1 InputFile OutputFile

Results:

ChildrenLog_10_1

Prent_Log_10_1

check_10_1

% dispatch 5 5 InputFile OutputFile

Results:

ChildrenLog_5_5

Prent_Log_5_5

check_5_5