A select with many constants in --query fails

[s-yata]

Description

A select with many constants (more than 1,024) in --query fails as follows:

[[-63,1449635050.73118,0.00283455848693848,"stack under flow in relative op",
 [["grn_expr_append_obj","expr.c",938],...

An error log says "too many constants".

2015-12-09 13:10:03.231572|e| too many constants.
2015-12-09 13:10:03.232183|e| /home/s-yata/git/groonga/lib/.libs/libgroonga.so.0(grn_expr_alloc_const+0xee) [0x7fcf90e9926e]
...
2015-12-09 13:10:03.232396|e| obj not assigned for GRN_OP_PUSH
2015-12-09 13:10:03.232625|e| /home/s-yata/git/groonga/lib/.libs/libgroonga.so.0(grn_expr_append_obj+0x1f88) [0x7fcf90e9dd18]
...
2015-12-09 13:10:03.232670|e| stack under flow in relative op
2015-12-09 13:10:03.232881|e| /home/s-yata/git/groonga/lib/.libs/libgroonga.so.0(grn_expr_append_obj+0x1286) [0x7fcf90e9d016]

The buffer size for constants is GRN_STACK_SIZE, like in #443 .

[s-yata]

The above commit (96427b0) updates grn_expr to allocate a new block when its buffer for constants is full.
Note that the address of each constant must not be modified in reallocation.

[s-yata]

The latest version can execute a select with 2,000 ORs in --query.

ORx2000.txt

However, please note that such a select may take much long time.

> select article --match_columns body --query '天気'
[[0,1449641126.55815,0.000834941864013672],
 [[[1],[["_id","UInt32"],["_key","UInt32"],["body","LongText"],["title","ShortText"]],
   [1,1,"今日は良い天気ですね．","本日は晴天なり"]]]]

> select article --match_columns body --query \
  '0 OR 1 OR 2 OR 3 OR 4 OR 5 OR 6 OR 7 OR 8 OR 9 OR \
   10 OR 11 OR 12 OR 13 OR 14 OR 15 OR 16 OR 17 OR 18 OR 19 OR \
   ... \
   OR 天気'
[[0,1449641126.55908,0.190096139907837],
 [[[1],[["_id","UInt32"],["_key","UInt32"],["body","LongText"],["title","ShortText"]],
   [1,1,"今日は良い天気ですね．","本日は晴天なり"]]]]