Enhance the FSDIR virtual table with a new "level" column. The query planner

knows how to optimize to avoid search deeper than the maximum requested level.

FossilOrigin-Name: 1ddc0f9e79c33957961bc1443ccb74d756a02cbd20850052079782e76aef2706

1 files changed, 91 insertions, 36 deletions

diff --git a/ext/misc/fileio.c b/ext/misc/fileio.c
index 96a7f82bd..c67fa9600 100644
--- a/ext/misc/fileio.c
+++ b/ext/misc/fileio.c
@@ -67,6 +67,7 @@
 **     data:  For a regular file, a blob containing the file data. For a
 **            symlink, a text value containing the text of the link. For a
 **            directory, NULL.
+**     level: Directory hierarchy level.  Topmost is 1.
 **
 **   If a non-NULL value is specified for the optional $dir parameter and
 **   $path is a relative path, then $path is interpreted relative to $dir. 
@@ -116,14 +117,16 @@ SQLITE_EXTENSION_INIT1
 /*
 ** Structure of the fsdir() table-valued function
 */
-                 /*    0    1    2     3    4           5             */
-#define FSDIR_SCHEMA "(name,mode,mtime,data,path HIDDEN,dir HIDDEN)"
+                 /*    0    1    2     3    4     5           6          */
+#define FSDIR_SCHEMA "(name,mode,mtime,data,level,path HIDDEN,dir HIDDEN)"
+
 #define FSDIR_COLUMN_NAME     0     /* Name of the file */
 #define FSDIR_COLUMN_MODE     1     /* Access mode */
 #define FSDIR_COLUMN_MTIME    2     /* Last modification time */
 #define FSDIR_COLUMN_DATA     3     /* File content */
-#define FSDIR_COLUMN_PATH     4     /* Path to top of search */
-#define FSDIR_COLUMN_DIR      5     /* Path is relative to this directory */
+#define FSDIR_COLUMN_LEVEL    4     /* Level.  Topmost is 1 */
+#define FSDIR_COLUMN_PATH     5     /* Path to top of search */
+#define FSDIR_COLUMN_DIR      6     /* Path is relative to this directory */
 
 /*
 ** UTF8 chmod() function for Windows
@@ -620,6 +623,7 @@ struct fsdir_cursor {
   sqlite3_vtab_cursor base;  /* Base class - must be first */
 
   int nLvl;                  /* Number of entries in aLvl[] array */
+  int mxLvl;                 /* Maximum level */
   int iLvl;                  /* Index of current entry */
   FsdirLevel *aLvl;          /* Hierarchy of directories being traversed */
 
@@ -738,7 +742,7 @@ static int fsdirNext(sqlite3_vtab_cursor *cur){
   mode_t m = pCur->sStat.st_mode;
 
   pCur->iRowid++;
-  if( S_ISDIR(m) ){
+  if( S_ISDIR(m) && pCur->iLvl+3<pCur->mxLvl ){
     /* Descend into this directory */
     int iNew = pCur->iLvl + 1;
     FsdirLevel *pLvl;
@@ -846,7 +850,11 @@ static int fsdirColumn(
       }else{
         readFileContents(ctx, pCur->zPath);
       }
+      break;
     }
+    case FSDIR_COLUMN_LEVEL:
+      sqlite3_result_int(ctx, pCur->iLvl+2);
+      break;
     case FSDIR_COLUMN_PATH:
     default: {
       /* The FSDIR_COLUMN_PATH and FSDIR_COLUMN_DIR are input parameters.
@@ -880,8 +888,11 @@ static int fsdirEof(sqlite3_vtab_cursor *cur){
 /*
 ** xFilter callback.
 **
-** idxNum==1   PATH parameter only
-** idxNum==2   Both PATH and DIR supplied
+** idxNum bit      Meaning
+**     0x01         PATH=N
+**     0x02         DIR=N
+**     0x04         LEVEL<N
+**     0x08         LEVEL<=N  
 */
 static int fsdirFilter(
   sqlite3_vtab_cursor *cur, 
@@ -892,20 +903,31 @@ static int fsdirFilter(
   fsdir_cursor *pCur = (fsdir_cursor*)cur;
   (void)idxStr;
   fsdirResetCursor(pCur);
+  int i;
 
   if( idxNum==0 ){
     fsdirSetErrmsg(pCur, "table function fsdir requires an argument");
     return SQLITE_ERROR;
   }
 
-  assert( argc==idxNum && (argc==1 || argc==2) );
+  assert( (idxNum & 0x01)!=0 && argc>0 );
   zDir = (const char*)sqlite3_value_text(argv[0]);
   if( zDir==0 ){
     fsdirSetErrmsg(pCur, "table function fsdir requires a non-NULL argument");
     return SQLITE_ERROR;
   }
-  if( argc==2 ){
-    pCur->zBase = (const char*)sqlite3_value_text(argv[1]);
+  i = 1;
+  if( (idxNum & 0x02)!=0 ){
+    assert( argc>i );
+    pCur->zBase = (const char*)sqlite3_value_text(argv[i++]);
+  }
+  if( (idxNum & 0x0c)!=0 ){
+    assert( argc>i );
+    pCur->mxLvl = sqlite3_value_int(argv[i++]);
+    if( idxNum & 0x08 ) pCur->mxLvl++;
+    if( pCur->mxLvl<=0 ) pCur->mxLvl = 1000000000;
+  }else{
+    pCur->mxLvl = 1000000000;
   }
   if( pCur->zBase ){
     pCur->nBase = (int)strlen(pCur->zBase)+1;
@@ -934,10 +956,11 @@ static int fsdirFilter(
 ** In this implementation idxNum is used to represent the
 ** query plan.  idxStr is unused.
 **
-** The query plan is represented by values of idxNum:
+** The query plan is represented by bits in idxNum:
 **
-**  (1)  The path value is supplied by argv[0]
-**  (2)  Path is in argv[0] and dir is in argv[1]
+**  0x01  The path value is supplied by argv[0]
+**  0x02  dir is in argv[1]
+**  0x04  maxdepth is in argv[1] or [2]
 */
 static int fsdirBestIndex(
   sqlite3_vtab *tab,
@@ -946,6 +969,9 @@ static int fsdirBestIndex(
   int i;                 /* Loop over constraints */
   int idxPath = -1;      /* Index in pIdxInfo->aConstraint of PATH= */
   int idxDir = -1;       /* Index in pIdxInfo->aConstraint of DIR= */
+  int idxLevel = -1;     /* Index in pIdxInfo->aConstraint of LEVEL< or <= */
+  int idxLevelEQ = 0;    /* 0x08 for LEVEL<= or LEVEL=.  0x04 for LEVEL< */
+  int omitLevel = 0;     /* omit the LEVEL constraint */
   int seenPath = 0;      /* True if an unusable PATH= constraint is seen */
   int seenDir = 0;       /* True if an unusable DIR= constraint is seen */
   const struct sqlite3_index_constraint *pConstraint;
@@ -953,25 +979,48 @@ static int fsdirBestIndex(
   (void)tab;
   pConstraint = pIdxInfo->aConstraint;
   for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
-    if( pConstraint->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
-    switch( pConstraint->iColumn ){
-      case FSDIR_COLUMN_PATH: {
-        if( pConstraint->usable ){
-          idxPath = i;
-          seenPath = 0;
-        }else if( idxPath<0 ){
-          seenPath = 1;
+    if( pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ ){
+      switch( pConstraint->iColumn ){
+        case FSDIR_COLUMN_PATH: {
+          if( pConstraint->usable ){
+            idxPath = i;
+            seenPath = 0;
+          }else if( idxPath<0 ){
+            seenPath = 1;
+          }
+          break;
         }
-        break;
-      }
-      case FSDIR_COLUMN_DIR: {
-        if( pConstraint->usable ){
-          idxDir = i;
-          seenDir = 0;
-        }else if( idxDir<0 ){
-          seenDir = 1;
+        case FSDIR_COLUMN_DIR: {
+          if( pConstraint->usable ){
+            idxDir = i;
+            seenDir = 0;
+          }else if( idxDir<0 ){
+            seenDir = 1;
+          }
+          break;
+        }
+        case FSDIR_COLUMN_LEVEL: {
+          if( pConstraint->usable && idxLevel<0 ){
+            idxLevel = i;
+            idxLevelEQ = 0x08;
+            omitLevel = 0;
+          }
+          break;
         }
-        break;
+      }
+    }else
+    if( pConstraint->iColumn==FSDIR_COLUMN_LEVEL
+     && pConstraint->usable
+     && idxLevel<0
+    ){
+      if( pConstraint->op==SQLITE_INDEX_CONSTRAINT_LE ){
+        idxLevel = i;
+        idxLevelEQ = 0x08;
+        omitLevel = 1;
+      }else if( pConstraint->op==SQLITE_INDEX_CONSTRAINT_LT ){
+        idxLevel = i;
+        idxLevelEQ = 0x04;
+        omitLevel = 1;
       }
     } 
   }
@@ -988,14 +1037,20 @@ static int fsdirBestIndex(
   }else{
     pIdxInfo->aConstraintUsage[idxPath].omit = 1;
     pIdxInfo->aConstraintUsage[idxPath].argvIndex = 1;
+    pIdxInfo->idxNum = 0x01;
+    pIdxInfo->estimatedCost = 1.0e9;
+    i = 2;
     if( idxDir>=0 ){
       pIdxInfo->aConstraintUsage[idxDir].omit = 1;
-      pIdxInfo->aConstraintUsage[idxDir].argvIndex = 2;
-      pIdxInfo->idxNum = 2;
-      pIdxInfo->estimatedCost = 10.0;
-    }else{
-      pIdxInfo->idxNum = 1;
-      pIdxInfo->estimatedCost = 100.0;
+      pIdxInfo->aConstraintUsage[idxDir].argvIndex = i++;
+      pIdxInfo->idxNum |= 0x02;
+      pIdxInfo->estimatedCost /= 1.0e4;
+    }
+    if( idxLevel>=0 ){
+      pIdxInfo->aConstraintUsage[idxLevel].omit = omitLevel;
+      pIdxInfo->aConstraintUsage[idxLevel].argvIndex = i++;
+      pIdxInfo->idxNum |= idxLevelEQ;
+      pIdxInfo->estimatedCost /= 1.0e4;
     }
   }