The decrease_count() function in the previous exercise currently returns 0 if sufficient resources are available and −1 otherwise. This leads to awkward programming for a process that wishes to obtain a number of resources: while (decrease_count(count) == -1) ; Rewrite the resource-manager code segment using a monitor and condition variables so that the decrease_count() function suspends the process until sufficient resources are available. This will allow a process to invoke decrease_count() by simply calling:

decrease_count(count);

The process will return from this function call only when sufficient resources are available.

Previous Code:

#define MAX_RESOURCES 5

int available_resources = MAX_RESOURCES;

When a process wishes to obtain a number of resources, it invokes the decrease_count() function:

/* decrease available_resources by count resources */

/* return 0 if sufficient resources available, */

/* otherwise return -1 */

int decrease_count(int count)

{ if (available_resources < count)

return -1;

else {

available_resources -= count;

return 0;

} }