From 7439a429d600ccc0c0248f433a088db2d24dc023 Mon Sep 17 00:00:00 2001 From: Rainer Jung Date: Thu, 5 Feb 2015 20:33:59 +0000 Subject: [PATCH] Expression parser: Optimize another concatenation case by using iteration instead of recursion. We have a relatively small recursion limit of about 10 operations. This is a compilation limit (a define). It can be hit if many expr vars or function calls are concatenated. The new optimization is very similar to the existing one, which optimizes consecutive concatenations in node2 of the tree. The new one optimizes consecutive concatenations in node 1. git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1657685 13f79535-47bb-0310-9956-ffa450edef68 --- server/util_expr_eval.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/server/util_expr_eval.c b/server/util_expr_eval.c index 9eb2792da1..b37319e9b9 100644 --- a/server/util_expr_eval.c +++ b/server/util_expr_eval.c @@ -103,7 +103,8 @@ static const char *ap_expr_eval_word(ap_expr_eval_ctx_t *ctx, node->node_arg2); break; case op_Concat: - if (((ap_expr_t *)node->node_arg2)->node_op != op_Concat) { + if (((ap_expr_t *)node->node_arg2)->node_op != op_Concat && + ((ap_expr_t *)node->node_arg1)->node_op != op_Concat) { const char *s1 = ap_expr_eval_word(ctx, node->node_arg1); const char *s2 = ap_expr_eval_word(ctx, node->node_arg2); if (!*s1) @@ -113,6 +114,30 @@ static const char *ap_expr_eval_word(ap_expr_eval_ctx_t *ctx, else result = apr_pstrcat(ctx->p, s1, s2, NULL); } + else if (((ap_expr_t *)node->node_arg1)->node_op == op_Concat) { + const ap_expr_t *nodep = node; + int n; + int i = 1; + struct iovec *vec; + do { + nodep = nodep->node_arg1; + i++; + } while (nodep->node_op == op_Concat); + vec = apr_palloc(ctx->p, i * sizeof(struct iovec)); + n = i; + nodep = node; + i--; + do { + vec[i].iov_base = (void *)ap_expr_eval_word(ctx, + nodep->node_arg2); + vec[i].iov_len = strlen(vec[i].iov_base); + i--; + nodep = nodep->node_arg1; + } while (nodep->node_op == op_Concat); + vec[i].iov_base = (void *)ap_expr_eval_word(ctx, nodep); + vec[i].iov_len = strlen(vec[i].iov_base); + result = apr_pstrcatv(ctx->p, vec, n, NULL); + } else { const ap_expr_t *nodep = node; int i = 1; -- 2.40.0