Replace dependency lookup cache with an STL unordered map

Annoyingly, rpmdbProvides() can get called with a NULL dcache so we
can't use a reference for passing it around. Dynamically allocating
it would be silly so just pass a pointer to the local variable around
instead (to avoid otherwise unnecessary code changes)

lib/depends.c

@@ -4,6 +4,9 @@
 
 #include "system.h"
 
+#include <string>
+#include <unordered_map>
+
 #include <rpm/rpmlib.h> /* rpmVersionCompare, rpmlib provides */
 #include <rpm/rpmtag.h>
 #include <rpm/rpmlog.h>
@@ -30,14 +33,7 @@ const char * const rpmEVR = VERSION;
 
 const int rpmFLAGS = RPMSENSE_EQUAL;
 
-#define HASHTYPE depCache
-#define HTKEYTYPE const char *
-#define HTDATATYPE int
-#include "rpmhash.H"
-#include "rpmhash.C"
-#undef HASHTYPE
-#undef HTKEYTYPE
-#undef HTDATATYPE
+typedef std::unordered_map<std::string,int> depCache;
 
 #define HASHTYPE filedepHash
 #define HTKEYTYPE rpmsid
@@ -508,24 +504,22 @@ int rpmtsAddEraseElement(rpmts ts, Header h, int dboffset)
 }
 
 /* Cached rpmdb provide lookup, returns 0 if satisfied, 1 otherwise */
-static int rpmdbProvides(rpmts ts, depCache dcache, rpmds dep, dbiIndexSet *matches)
+static int rpmdbProvides(rpmts ts, depCache *dcache, rpmds dep, dbiIndexSet *matches)
 {
  const char * Name = rpmdsN(dep);
  const char * DNEVR = rpmdsDNEVR(dep);
  rpmTagVal deptag = rpmdsTagN(dep);
- int *cachedrc = NULL;
  rpmdbMatchIterator mi = NULL;
  Header h = NULL;
  int rc = 0;
  /* pretrans deps are provided by current packages, don't prune erasures */
  int prune = (rpmdsFlags(dep) & (RPMSENSE_PRETRANS|RPMSENSE_PREUNTRANS)) ? 0 : 1;
- unsigned int keyhash = 0;
 
  /* See if we already looked this up */
  if (prune && !matches) {
- keyhash = depCacheKeyHash(dcache, DNEVR);
- if (depCacheGetHEntry(dcache, DNEVR, keyhash, &cachedrc, NULL, NULL)) {
- rc = *cachedrc;
+ auto ret = dcache->find(DNEVR);
+ if (ret != dcache->end()) {
+ rc = ret->second;
  rpmdsNotify(dep, "(cached)", rc);
  return rc;
  }
@@ -600,7 +594,7 @@ static int rpmdbProvides(rpmts ts, depCache dcache, rpmds dep, dbiIndexSet *matc
  /* Cache the relatively expensive rpmdb lookup results */
  /* Caching the oddball non-pruned case would mess up other results */
  if (prune && !matches)
- depCacheAddHEntry(dcache, xstrdup(DNEVR), keyhash, rc);
+ dcache->insert({DNEVR, rc});
  return rc;
 }
 
@@ -672,7 +666,7 @@ static dbiIndexSet unsatisfiedDependSet(rpmts ts, rpmds dep)
  * @param dep dependency
  * @return 0 if satisfied, 1 if not satisfied
  */
-static int unsatisfiedDepend(rpmts ts, depCache dcache, rpmds dep)
+static int unsatisfiedDepend(rpmts ts, depCache *dcache, rpmds dep)
 {
  tsMembers tsmem = rpmtsMembers(ts);
  int rc;
@@ -801,7 +795,7 @@ static int unsatisfiedDepend(rpmts ts, depCache dcache, rpmds dep)
 }
 
 /* Check a dependency set for problems */
-static void checkDS(rpmts ts, depCache dcache, rpmte te,
+static void checkDS(rpmts ts, depCache *dcache, rpmte te,
  const char * pkgNEVRA, rpmds ds,
  rpm_color_t tscolor)
 {
@@ -822,7 +816,7 @@ static void checkDS(rpmts ts, depCache dcache, rpmte te,
 }
 
 /* Check a given dependency against installed packages */
-static void checkInstDeps(rpmts ts, depCache dcache, rpmte te,
+static void checkInstDeps(rpmts ts, depCache *dcache, rpmte te,
  rpmTag depTag, const char *dep, rpmds depds, int neg)
 {
  Header h;
@@ -872,7 +866,7 @@ static void checkInstDeps(rpmts ts, depCache dcache, rpmte te,
  free(ndep);
 }
 
-static void checkInstFileDeps(rpmts ts, depCache dcache, rpmte te,
+static void checkInstFileDeps(rpmts ts, depCache *dcache, rpmte te,
  rpmTag depTag, rpmfi fi, int is_not,
  filedepHash cache, fingerPrintCache *fpcp)
 {
@@ -979,7 +973,7 @@ int rpmtsCheck(rpmts ts)
  rpmtsi pi = NULL; rpmte p;
  int closeatexit = 0;
  int rc = 0;
- depCache dcache = NULL;
+ depCache _dcache, *dcache = &_dcache;
  filedepHash confilehash = NULL; /* file conflicts of installed packages */
  filedepHash connotfilehash = NULL; /* file conflicts of installed packages */
  depexistsHash connothash = NULL;
@@ -1003,10 +997,6 @@ int rpmtsCheck(rpmts ts)
  if (rdb)
  rpmdbCtrl(rdb, RPMDB_CTRL_LOCK_RO);
 
- /* XXX FIXME: figure some kind of heuristic for the cache size */
- dcache = depCacheCreate(5001, rstrhash, strcmp,
- (depCacheFreeKey)rfree, NULL);
-
  /* build hashes of all confilict sdependencies */
  confilehash = filedepHashCreate(257, sidHash, sidCmp, NULL, NULL);
  connothash = depexistsHashCreate(257, sidHash, sidCmp, NULL);
@@ -1117,7 +1107,6 @@ int rpmtsCheck(rpmts ts)
  rpmdbCtrl(rdb, RPMDB_CTRL_UNLOCK_RO);
 
 exit:
- depCacheFree(dcache);
  filedepHashFree(confilehash);
  filedepHashFree(connotfilehash);
  depexistsHashFree(connothash);