changed eviction

path_oram.cpp

@@ -9,6 +9,7 @@
 #include <vector>
 #include <string>
 #include <unordered_map>
+#include <unordered_set>
 #include <algorithm>
 #include <random>
 #include <cstdlib>
@@ -17,7 +18,7 @@ using namespace std;
 
 // ORAM parameters (for demonstration)
 const int TREE_HEIGHT = 3;            // Height of the tree (number of levels - 1)
-const int BUCKET_CAPACITY = 4;        // Maximum number of blocks per bucket
+const int BUCKET_CAPACITY = 3;        // Maximum number of blocks per bucket
 const int NUM_LEAVES = 1 << TREE_HEIGHT;             // 2^TREE_HEIGHT leaves
 const int NUM_BUCKETS = (1 << (TREE_HEIGHT + 1)) - 1;  // Total number of buckets in a complete binary tree
 const string STATE_FILE = "oram_state.db";           // File to persist ORAM state
@@ -148,25 +149,26 @@ void saveState() {
     outfile.close();
 }
 
-// Eviction: Write blocks from the stash back into the tree along the given path.
-// For each bucket on the path, try to place blocks from the stash that "belong" to that bucket.
-void evictPath(const vector<int>& path) {
+void evictPath(vector<int> path) {
+    reverse(path.begin(), path.end()); // Evict from leaf to root
+
     for (int bucketIdx : path) {
         int capacity = BUCKET_CAPACITY - tree[bucketIdx].size();
         if (capacity <= 0) continue;
-        // Iterate over stash and try to place blocks whose assigned leaf's path includes this bucket.
-        for (auto it = stash.begin(); it != stash.end(); ) {
-            int assignedLeaf = posMap[it->id]; // Each block’s current assigned leaf.
+
+        vector<int> toRemove;
+        for (auto it = stash.begin(); it != stash.end(); ++it) {
+            int assignedLeaf = posMap[it->id];
             vector<int> blockPath = getPathIndices(assignedLeaf);
             if (find(blockPath.begin(), blockPath.end(), bucketIdx) != blockPath.end()) {
                 tree[bucketIdx].push_back(*it);
-                it = stash.erase(it);
-                capacity--;
-                if (capacity == 0) break;
-            } else {
-                ++it;
+                toRemove.push_back(it->id);
+                if (--capacity == 0) break;
             }
         }
+        for (int id : toRemove) {
+            stash.erase(remove_if(stash.begin(), stash.end(), [&](Block b) { return b.id == id; }), stash.end());
+        }
     }
 }