ProcessList: fix quadratic process removal when scanning

This commit changes ProcessList_scan to lazily remove Processes by
index, which is known, instead of performing a brute-force search by
pid and immediately reclaiming the lost vector space via compaction.

Searching by pid is potentially quadratic in ProcessList_scan because
the process we are searching for is always at the back of the vector
(the scan starts from the back of the vector). Additionally, removal
via Vector_remove immediately reclaims space (by sliding elements
down).

With these changes process removal in ProcessList_scan is now linear.

Changes:
  * ProcessList: add new ProcessList_removeIndex function to remove
    by index
  * Vector: add Vector_softRemove and Vector_compact functions to
    support lazy removal/deletion of entries Vector_softRemove
    Vector_compact
  * Vector: replace Vector_count with Vector_countEquals since it only
    used for consistency assertions.

1 files changed, 0 insertions, 7 deletions

diff --git a/Process.c b/Process.c
index 6c7b3263..600659c9 100644
--- a/Process.c
+++ b/Process.c
@@ -1095,13 +1095,6 @@ bool Process_sendSignal(Process* this, Arg sgn) {
    return kill(this->pid, sgn.i) == 0;
 }
 
-int Process_pidCompare(const void* v1, const void* v2) {
-   const Process* p1 = (const Process*)v1;
-   const Process* p2 = (const Process*)v2;
-
-   return SPACESHIP_NUMBER(p1->pid, p2->pid);
-}
-
 int Process_compare(const void* v1, const void* v2) {
    const Process* p1 = (const Process*)v1;
    const Process* p2 = (const Process*)v2;